Question

HELP ME PRETTY PLEASEEE

Answer 1

Answer:

5a + 2b + 8

Step-by-step explanation:

The third side is the perimeter minus the sum of the first two sides.

$18a+6b+15-(5a+7+8a+4b) \\ \\ =18a+6b+15-(13a+4b+7) \\ \\ =5a+2b+8$

Answer 2

Answer:

$c=5a+2b+8$.

Step-by-step explanation:

1. Create an expression.

Using the fact that the perimeter of a triangle is just the sum of the lengh of all its sides, then the expression "$18a+6b+15$" is the result of adding up all the sides of this triangle. Then, if we have 2 of the 3 sides, the resulting side must measure the difference between the perimeter and the sum of the 2 given sides.This is how to write it:

$18a+6b+15-((5a+7)+(8a+4b))=c$; c is the given name for the third side.

2. Simplify the expression.

$c=18a+6b+15-(5a+7+8a+4b)\\ \\c=18a+6b+15-(13a+7+4b)\\ \\c=18a+6b+15-13a-7-4b\\ \\c=5a+2b+8$

3. Express the result.

$c=5a+2b+8$.