Step-by-step explanation:
here's the answer to your question
we know that Bob can do the whole job in 14 hours, how much of the work has he done in 1 hour only? well since he can do the whole lot in 14 hours in 1 hour he has only done 1/14 th of the job.
we know that James can do it in 18 hours, a bit slower, so in 1 hour he has done only 1/18 th of the job.
let's say it takes both of them working together say "t" hours, so in 1 hour Bob has done (1/14) of the work whilst James has done (1/18) of the work, the whole work being t/t or 1 whole, so for just one hour that'd 1/t done by both Bob and James.

If you solve for x you get:
x=(<span><span><span>5/2)</span>y</span>+<span>10
</span></span>
If you solve for y you get:
y=(<span><span><span>2/5)</span>x</span>−<span>4</span></span>