Answer:
a) 8x + 5x = 13x
b) 9f + 10f - 12f = 7f
Step-by-step explanation:
For part b, just solve from left to right normally, since adding and subtracting are inverse operations. (Inverse operation; meaning they are opposites of each other.)
So 9 + 10 = 19, and 19 - 12 = 7.
Hope this helps you :)
