How do you find the missing measurement

The angle that has a little square in the corner, is 90 degrees. so you can add 90 and 72 which is 162 and take 180-162 because the line that is on top of them is a straight line. so z= 18 degrees. take 180-72 because the line left to 72 is also straight so x=108.
we know z already equals 18 so add 90+18= 108. subtract 180-108 =72
z=18
x=108
y=72

the image of (6, 9) under a dilation is (4, 6). the scale factor is

b. 2/3