Eliminate variable y to solve for x in the given equations.

Use the coefficients of y from Eq.1 and Eq.2 as a multiplier to eliminate the y variables. Then multiply equation 1 throughout by 7 and label it equation 3

Multiply equation 1 throughout by 3 and label it equation 4

Subtract Eq.4 from Eq.3 Equation (3) – Equation (4)

Note: When the sign of common coefficients are different, the two coefficients are added but if the common coefficients are of the same or of equal signs, the coefficients are substracted. In this case, 21y and 21y have same signs and coefficients and were substracted

Divide through by the coefficient of x

Now find the value of y where x = -25 using equation 2