Chapter 4 – Planning with limiting factors Question help

Please see question below, at work typing this out, spent half an hour on it last night and could not figure it out :S;

A: X=0 y=3,333.3
Z=10x + 5y= 10(0) + 5(3333.3) = $16,666.50

B: Solving 0.18x+0.03y=100, and 0.05x +0.02y =50
Gives x=238.1 and y=1904.8
Z=10(238.1) + 5(1,904.8) = $11,905

C: Solving 0.05x + 0.02y= 50 and 0.02x + 0.05y=40
Gives x=809.5 and y=476.2
Z=10(809.5)=5(476.2)=$10476

D: X=2,000 y=0
Z=10(2000) + 5 (0) = $20,000

I get part A of this and that’s about it. Part B is where I’m completely lost how X=238.1 and Y=1904.8 is worked out?

Kaplan text book doesn’t really have a breakdown, just assumes you should know…