What is the measure of angle j in the triangle below? drawing is not to scale

Could somebody me with this radical simplification?

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

What is the domain of the given function? {(3,-2), (6, 1), (-1, 4), (5,9), (-4, 0); o {x | x= -4,-1, 3, 5, 6} o {yl y = -2,0, 1,4,9} o {x|x = -4,-2, -1,0, 1, 3, 4, 5, 6, 9} o y y = 4,-2, -1, 0, 1, 3, 4, 5, 6, 9}