Answer:

Explanation:
We are given the expression:

We want to find the value of the expression when y=8 and z=9. Therefore, we must substitute 8 in for y and 9 in for z.

Solve according to PEMDAS: Parentheses, Exponents, Multiplication, Division, Addition, Subtraction.
Multiply 5 and 8.

Multiply 2 and 9.

Subtract 18 from 40.

The value of the expression 5y-2z at y=8 and z=9 is 22.