Anyone know the answer please help

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

Asales representative from a local radio station is trying to convince the owner of a small fitness club to advertise on her station. the representative says that if the owner begins advertising on the station today, the club's total number of members will grow exponentially each month. she uses the given expression to model the number of club members, in hundreds, after advertising for t months.

Perry observes the opposite parallel walls of a room in how many lines do the plains containing the walls intersect