Question:

Evaluate each expression:

1. 9x + 8y, when x = 4 and y = 5

2. 2x + 8x, when x = 3

3. 4y + 7y, y = 5

4. 10x + 18y, when x = 4 and y = 5

5. x + 8y, when x = 2 and y = 1/4

6. 9x + 8y, when x = 1/3 and y = 1/4

7. 3x + 7y, when x = 8 and y = 4

8. 12x + 16y, when x = 1/4 and y = 5