The solutions to 15(2a – 2) = 5(a2 – 1) are:

Interpret a2 as a². Divide both sides of 15(2a − 2) = 5(a² − 1) by 5 to get 6a − 6 = a² − 1, or a² − 6a + 5 = 0. Factoring gives (a − 1)(a − 5) = 0, so a = 1 or a = 5. Choice C lists these two solutions.

AI-written and checked against the verified answer.