Examples for secondary school students - page 76

1. Home cleaning
Mr. Smith is cleaning up a big mess at home. In the closet, he finds a solution that is 5% bleach, and another stronger solution that is 20% bleach. For this particular job, he needs 600mL of 15% bleach. How much of each type (to the nearest mL) should he.
2. Rectangular plot
The dimensions of a rectangular plot are (x+1)m and (2x-y)m. If the sum of x and y is 3m and the perimeter of the plot is 36m. Find the area of the diagonal of the plot.
3. Three unknowns
Solve the system of linear equations with three unknowns: A + B + C = 14 B - A - C = 4 2A - B + C = 0
4. Lee is
Lee is 8 years more than twice Park's age, 4 years ago, Lee was three times as old. How old was Lee 4 years ago?
5. Pooja
Pooja and Deepa age is 4:5, 4 years back it was 8:11. What is the age of Pooja now?
6. Two boats
Two boats are located from a height of 150m above the surface of the lake at depth angles of 57° and 39°. Read the distance of both boats if the sighting device and both ships are in a plane perpendicular to the surface of the lake.

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