I need to know how to solve this equation?

Your picture shows the first step: use the distributive property to eliminate parentheses.
  5*7 -5*x = 2*x -3
Now, you have an equation with a constant and an x-term on each side. I like to pick the x-term with the smallest (most-negative) coefficient and add its opposite to the equation.

Adding 5x, we have
  35 = 7x -3
Adding 3 will get the x-term on one side and the constant on the other
  38 = 7x
Now, we divide by the coefficient of x
  38/7 = x = 5 3/7

This is the correct answer, even though it is not an integer.

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Check
  5(7 -(5 3/7)) = 2(5 3/7) -3 . . . . substitute for x in the original equation
  5(1 4/7) = 10 6/7 -3 . . . . . . . . . evaluate the parentheses on the left, do the multiplication on the right
  5 20/7 = 7 6/7 . . . . . . . . . . . . do the multiplicaton on the left, the subtraction on the right
  5 +2 6/7 = 7 6/7 . . . . . . . . . . . rewrite 20/7, realize 5+2=7. true