Question

Two welders working together can complete a job in 6 h. One of the welders, working alone, can complete the task in 15 h. How long would it take the second welder, working alone, to complete the task?

Answer 1

The answer is 10 hours

Answer 2

Ur asking a bunch of these kind of rate problems xD
$6 ( \frac{1}{15} + \frac{1}{x} )=1$
In 6 hrs, the welder who does 1/15 of the job in 1 hr and the welder who does 1/x in 1 hr, complete the job (6 hrs.)
$\frac{1}{15} + \frac{1}{x} = \frac{1}{6}$
Multiply 30 on both sides to cancel out the fractions and we get:
$2 + \frac{30}{x} =5$
Solving for x:
30/x=3
3x=30
x=10
The second welder would take 10 hours.