Pump 1 takes 7minutes to fill my 20 gallon gas tank. Pump 2 takes 13 minutes to fill my tank. How long would it take if I could use both tanks at the same time?

Question

dumbcow · Answer

$$\frac{20}{7}x + \frac{20}{13}x = 20$$
add fractions
7*13 = 91 
$$\frac{(20)(13)x + (20)(7)x}{91} = 20$$
multiply 91 on both sides
add like terms
$$400x = 1820$$
$$x = 4.55$$

anonymous · Answer

ok i understand the answer but not understanding the directions plz make them clearer

anonymous · Answer

is answer coorect?

anonymous · Answer

dont know

dumbcow · Answer

for pump 1 we need to find the rate of gall/min ->20/7
pump 2  rate is 20/13 gal/min
if we multiply this rate by time we get a num of gallons
this time is represented by x, the amount of time to fill up using both pumps
total num of gallons needed is 20 so it equals 20

anonymous · Answer

ok gotcha

anonymous · Answer

i just have to explain in detail how i got my answer and show my work just alittle confused on your work