Frank and Hank are farmers. Frank can plant a field in 3 hours, but when he works with Hank, they

can plant a field in 1 hour. How long, in minutes, would it take Hank to plant a field by himself?

2 answers

franks rate = 1/3
Hanks rate = 1/x
combined rate = 1/3 + 1/x
= (x+3)/(3x)

1/( (x+3)/(3x) ) = 1
3x/(x+3) = 1
3x = x + 3
2x = 3
x = 1.5

It would take him 1.5 hours
1st grade or waht