Ding got an x in math.

X-9=(87+83+82+X)/4

X-9=(252+X)/4

(X-9)*4=(252+X)/4*4

(X-9)*4=252+X

4X-9*4=252+X

4X-36-X=252+X-X

3X-36=252

3X=288

X=96

The basis of solving equations

1, move terms and symbols: move some terms in the equation from one side of the equation to the other side of the previous symbol, and add, subtract, multiply and divide, change, multiply and divide;

2, the basic properties of the equation:

Adding (or subtracting) the same number or the same algebraic expression on both sides of the (1) equation at the same time, the result is still an equation. Represented by letters: if a=b, c is a number or an algebraic expression.

(2) Both sides of the equation are multiplied or divided by the same number that is not 0 at the same time, and the result is still an equation. Represented by letters: if a=b, c is a number or an algebraic expression (not 0).