Question 245846
If a machine A makes 1000 gidgets in 4 hours, and machine B makes 1000 gidgets in 8 hours, how long will it take both machines to make 1000 gidgets??
.
Let x = time it takes for both machines to make 1000 gidgets
then
x [1000/4 + 1000/8] =  1000
Multiplying both sides by 8:
x [2000 + 1000] =  8000
x [3000] =  8000
x =  8000/3000
x = 8/3 hours
or
x = 2 hours and 40 minutes