Y+=15;

y*=4;

z-=18;

a/=2;

This is simply programming language shorthand.

Explanation:

y = y + 15

y = y * 4

z = z - 18

a = a / 2

I hope you see the pattern. It is setting the variable equal to the variable with the operation appended to it at the degree of the number:

variable = variable (operation) number

variable (operation)= number

can you include the statments that complete the question ?

power left de cliffs or inoonsw