Answer:
The answer is D.
Sum means addition. So, you would be adding a and b. Remember this; a - b = difference, a * b = product, a ÷ b = quotient, and a + b = sum. Good luck!
-12+3b-1=-5-b
Combine like terms to get:
3b-13=-5-b
Add 13 to both sides:
3b= 8-b
Add b to both sides:
4b=8
Divide both sides by 4:
4b/4=8/4
b=2
Final answer
b=2
Since they are similar both dimensions would have the same ratio. The ratio of 5 and 15 is 3. 15 is 3 times larger than 5, so the unknown dimension is 3 times larger than the known dimension.
3 x 10 = 30
The unknown dimension is 30