First you can subtract y from 180 (number of degrees in a straight line) to find the value of x and z combined; 180-80=100. This means x+z=100.
Since you know that x:z is 2:3, and they add up to 100, you can find x and z. Add 2+3 (the ratios) to get 5. There are 5 parts in 100. The value of each part is 20 (divide 100/5). The value of x is 2 parts, and the value of z is 3 parts. 2 parts of 20 is 40 (multiply 2*20). 3 parts of 30 is 60 (multiply 3*20).
Now you know that x is 40 and y is 60.
You can also check your answer.
40+80+60 equals 180.