Answer:
- b = P - a - a - B
- b = P - 2a - B
Step-by-step explanation:
The perimeter is the sum of the lengths of the sides, so is ...
P = B + a + b + a
Subtracting the terms that are not "b" from both sides of the equation, you get
P - a - a - B = b
Swapping sides of the equal sign, this matches the first choice:
b = P - a - a - B
The two "-a" terms are "like terms" so can be added together. The result matches the second choice.
b = P - 2a - B
