Question

An equilateral triangle has sides of length s. If each side is increased by 15​, represent the new perimeter in terms of s.

Answer 1

We know that an equilateral triangle has all sides equal.
Initial perimeter = s + s + s = s
Each side has been increases by then the new perimeter is:

(s+15) + (s+15) + (s+15) = 3s + 45

So the new perimeter = 3s + 45