Simplify the square root of 5 times 3 square root of 5

Which of the following is most likely the next step in the series? a3z, b6y, c9x, d12w, е15v, f18u

Josh has a rewards card for a movie theater he receives 15 points for becoming a rewards card holder he earns 3.5 points for each visit to the movie theater he needs at least 55 points to earn a free movie ticket which inequality can josh use to determine x, the minimum number of visits he needs to earn his first free movie ticket.

Lola says these two expressions have the same value. expression a expression b which explains whether lola is correct?