How do you factor this? I’m kinda confuse about how you do factoring

Given the two similar triangles, how do i find the missing length? if a=4, b=5, and b'=7.5 find a'

Write the factored form of this trinomial 9x^2+18x-7

Bo is buying a board game that usually costs bb dollars. the game is on sale, and the price has been reduced by 18\%18%. which of the following expressions could represent how much bo pays for the game? choose 2 answers: choose 2 answers: (choice a) a 0.82b0.82b (choice b) b 1.18b1.18b (choice c) c b-0.18b−0.18 (choice d) d b-18b−18 (choice e) e b-0.18bb−0.18b