HELP pls help I will give brainiest

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

Manuela claims that and are congruent. which statement best describes her claim? she is incorrect because the segments do not have the same orientation. she is incorrect because the segments do not have the same length. she is correct because the segments have the same length. she is correct because the segments have the same orientation.

Idon't get undoing if its pass adding and subtracting so can someone ? x-2 over 5 = 18