Final answer:
To find the value of 5y - 9, solve the equation -3y + 5 = 8 for y, substitute the value of y into 5y - 9, and simplify the expression. The final result is -14.
Step-by-step explanation:
To find the value of 5y - 9, we can first solve the equation -3y + 5 = 8 to find the value of y. Subtracting 5 from both sides, we get -3y = 3. Dividing by -3, we find that y = -1. Now we can substitute this value into the expression 5y - 9. Substituting y = -1, we get 5(-1) - 9 = -5 - 9 = -14.