# The coal

The coal stock would be enough to heat a larger room for 12 weeks, a smaller one for 18 weeks. It was heated for four weeks in both rooms, then only in a smaller one. How long was the coal stock enough?

Correct result:

x =  12

#### Solution:

$z=12a \ \\ z=18b \ \\ z - 4a -4b=b \cdot \ x \ \\ \ \\ z - 4(z/12)-4 \cdot \ (z/18)=(z/18) \cdot \ (x-4) \ \\ \ \\ \ \\ 1 - 4 \cdot \ (1/12) - 4 \cdot \ (1/18)=1/18 \cdot \ (x-4) \ \\ \ \\ 2x=24 \ \\ \ \\ x=12$

We would be pleased if you find an error in the word problem, spelling mistakes, or inaccuracies and send it to us. Thank you!

Tips to related online calculators
Do you have a linear equation or system of equations and looking for its solution? Or do you have quadratic equation?
Do you want to convert time units like minutes to seconds?

## Next similar math problems:

• Receiving heat
How many degrees Celsius was an iron cylinder weighing 300 g heated in a water bath if it received heat of 7.2 kJ? (specific heat capacity of iron c = 0.46kJ/kg / ºC)
• Two rooms
Woman cleans the room in 30 minutes a man in 90 minutes. How long will take they clean two rooms?
• Tonic
One package tonic consume Mom 12 weeks and daughter for 14 weeks. 4 weeks they use the same cream together and then only daughter. How many weeks endured tonic to daughter then?
• Four pavers
Four pavers would pave the square in 18 days. How many pavers do you need to add to done work in 12 days?
• Positional energy
What velocity in km/h must a body weighing 60 kg have for its kinetic energy to be the same as its positional energy at the height 50 m?
• Pool
If water flows into the pool by two inlets, fill the whole for 19 hours. The first inlet filled pool 5 hour longer than the second. How long pool take to fill with two inlets separately?
• Bulb
A 60 W bulb consumes 0.12 kWh of electricity. How long did she stand light without a break?
• Pond
A pond with two open floodgates will emptied in 20 days. A larger floodgate will emptied whole pond in 30 days. For how long would he be emptied with a smaller floodgate.
• Electric work
Calculate the work done by the electric forces passing the current of 0.2 A through the bulb in 10 minutes if the bulb is connected to a 230 V power supply.
• Motorcycle engine
The motorcycle engine has a constant power of 1.2 kW for 0.5 hours. How much work does the engine do? Express work in kWh and Ws units.
• Motor physics
Car traveling at 130 km/h on the highway. Pulling power of the motor is 8 kN. Determine engine power in kW.
• Cooker
A current of 2A passes through the immersion cooker at a voltage of 230V. What work do the electric field forces in 2 minutes?