Question

Ella simplifies (3b+4r)+(-2b-r) and says the result is b+5r. What error did Ella make?

A. Ella incorrectly combined the b coefficients. The correctly simplified expression is 5b+5r.

B. Ella incorrectly combined the b coefficients. The correctly simplified expression is -b+5r.

C. Ella incorrectly combined the r coefficients. The correctly simplified expression is b-5r.

D. Ella incorrectly combined the r coefficients. The correctly simplified expression is b+3r.

Answer 1

D is the answer.
3b+(-2b)= 1b (same as 3-2=1)
4r+(-r)= 3r (same as 4-1=3)
When you add a negative, you subtract.

Answer 2

The correct answer is (D).
(3b + 4r) + (-2b - r) = (3b - 2b) + (4r - r) = b + 3r
not
b + 5r
* Ella added (4r + r) instead subtracting (4r - r), thus she got the wrong answer.