Question

Solve for b in the equation –b + 21 = –13.

A. b = 9
B. b = –9
C. b = 34
D. b = –34

Answer 1

-b + 21 = -13

Move constant to the right and change the sign

-b = -13 - 21

Calculate the difference

-b = -34

Change the signs on both sides of the equation

So, b = 34

Answer 2

C. b = 34

Explanation:

Given

-b+21= -13

To solve this type of equations that only involve one variable, we have to isolate the variable at on side of the equation. So, for the given equation

We will subtract 21 from both sides

-b+21-21=-13-21

-b= -34

As the minus sign is on both sides of the equation, it will be cancelled and

b=34

So, option C is the correct answer ..