Equation - 8th grade (13y) - math problems

Ducats
The king divided the ducats to his three sons in a ratio of 2: 5: 4. How many ducats the king divided them if the youngest received 260 ducats, which was the least of all sons.
Runners
If John has a running speed of 3.5miles per hour and Lucy has a speed of 5 miles per hour. If John starts running at 10:00 am and Lucy starts running at 10:30 am, at what time will they meet? (as soon as possible)
Aircraft angines
The two engines of the aircraft are enough to supply the fuel for five hours of operation. However, one of the engines has a malfunction and thus consumes one-third more fuel. How long can the plane be in the air before it runs out of fuel? After an hour
Alcohol mixing
How much 64% of the alcohol must be poured into 6 liters of 85% alcohol to produce 79% alcohol?
Nádoba
Nádoba tvaru kostky je naplněna vodou do poloviny své výšky. Pokud dolijeme 20 l vody, bude nádoba naplněna do tří čtvrtin své výšky. Jaký je objem celé nádoby?
Buttons
Men's shirt has sewn 9 buttons and blouse 3 buttons. Together they sewed 60 pieces and consumed 390 buttons. How many shirts?
Unknown number
15% of the unknown number is 18 less than 21% of the same number. What is the unknown number?
Scholarship
The annual scholarship of the best student and second-best student in the class is 3500 euros in total. The best student scholarship in 8 months is the same as the second-best student scholar in the class for the whole year. How big is the annual scholars
Baking muffins
Aunt Polly is baking muffins at a speed of 4 muffins per minute. Tom comes into the kitchen when Aunt Polly has 12 muffins, and begins to eat these muffins at a speed of 6 muffins per minute. When he finally leaves the kitchen, there are 4 muffins at the
Panel house
The construction company has two groups of workers. Group A has more members than B. Panel house was insulated by group A in 10 days. The same block of flats was insulated together in 6 days. How many days would group B block insulate?
Uboid volume
Calculate the cuboid volume if the walls are 30cm², 35cm², 42cm²
Mary
Mary is 12 years old, which is 40% of the age of her mother. How many percent of her mother's age will Mary have after the next 12 years?
Trio ratio
Hans, Alena and Thomas have a total of 740 USD. Hans and Alena split in the ratio 5: 6 and Alena and Thomas in the ratio 4: 5. How much will everyone get?
Christmas or Easter
Please calculate this example by the Venn equation. They asked 73 students whether they like Christmas or Easter. 34 of them like one of the holidays. 39 loves Easter. There are twice as many students who wish both holidays than those who only love Ea
Tributaries
The pool can be filled with two different tributaries. The first inflow would fill the pool in 18 hours, both in 6 hours. How many hours would the pool filled with a second inflow?
Two machines
The first machine can produce parts in 24 hours, the second in 16 hours. The first started working in the morning at 6:00 pm. Second at 10:00 o'clock. At what hour were all parts made?
Pouring alcohol
100 liters of alcohol has 70% How many liters of water need to be added to have 60% alcohol?
Cheetah vs antelope
When the cheetah began chasing the antelope, the distance between them was 120 meters. Although the antelope was running at 72km/h, the cheetah caught up with it in 12 seconds. What speed was the cheetah running?
Fruit salad
The fruit salad is prepared from oranges and bananas. One kilogram of oranges costs 30 CZK and one kilogram of bananas costs 18 CZK. How many kilograms of bananas need to be added to half a kilogram of oranges to produce a fruit salad worth CZK 21 per 1 k
Rectangles
Vladimir likes to draw rectangles. Yesterday he created all rectangles that had sides in centimeters and a circumference of 18 cm. How many rectangles of different dimensions have been drawn?