In figure, what is the value of y? a. 20° b. 90° c. 40° d. 30°

First, find the value of x.  Note that the angles x, 0.5x and 3x sum up to 4.5x, and that this sum has the value 180 degrees.  Solving this equation for x, we get x = 40 degrees.

Now, 0.5x and 0.5y are vertical angles, and thus x = y.  So, with x being 40 degrees, y = 40 degrees.

a 4/6 = 9/12   not proportional

step-by-step explanation:

to find which are not proportional, we can use cross products

if it is true, they are proportional.   if it is not true, they are not proportional.

a 4/6 = 9/12

4* 12 = 6*9

48 = 54

not this is not proportional  

b 2/3 = 12/18  

2* 18 = 3 * 12

36 = 36

this is proportional

c 5/4 = 10/8  

5*8 = 4*10

40 = 40

this is proportional

d 7/5 = 35/25

7*25 = 5 * 35

175 = 175

is proportional