Answer is 7
Step by step
We use the substitution method to answer this.
mx -y = ?
m = 5, x = 3, y = 8
Substitute numbers in for your letters
(5) * (3) - (8)
Rule for math is multiply and divide before add and subtract (PEMDAS)
(5) * (3) = 15
15 - (8) = 7
Your answer is 7