Solving systems of linear equations with the substution method

how would I solve the system below using the substitution method?

4x-y=100
0.05x-0.06y=-32

the book says the answer is (200,700) but I can't figure out how to get that answer.
Help please? What am I missing?

4x-y=100 → y = 4x-100 substitution in the next equation
0.05x-0.06y=-32 → 0.05x-0.06(4x-100)=-32
0.05x – 0.24x + 6 = -32
-0.19x = -38
x = -38/-0.19 = 200 ← substitution at one of the main equation
4x-y=100 → 4(200) – y = 100
y = 800 – 100 = 700
(x, y) = (200, 700)