Answer:
CB = 20 or D
Explanation:
Remark
You have a proportion. A proportion consists of 2 equal ratios. Three parts of the Proportion of 4 much be known. Then you can solve for the 4th.
Formula
Large vertical / Small Vertical = large horizontal / Small horizonal. Notice how Large goes on top of the ratios and small on the bottom.
Givens
Large Vertical: 8 feet
Small Vertical: 5 feet
Large horizontal: CA + 12.5 feet
Small Horizontal: 12.5
Solution
8/5 = (CA + 12.5) / 12.5 Cross Multiply
5(CA + 12,5) = 8 * 12.5 Remove the Brackets
5CA + 62.6 = 100 Subtract 62.5 from both sides.
5CA = 37.5 Divide by 5
CA = 7.5
CB = CA + 12.5
CB = 7.5 + 12.5
CB = 20
Answer
D