Solve by the method of your choice (addition or substitution)

Question

7x-4y=9

2x+y=9

Answer 1

Substitution method

Given equations are 7x - 4y = 9 ---> (1)

2x + y = 9

Substract 2x  from each side.

y  = -2x + 9 ---> (2)

From (2) substitute the y  value in (1).

7x - 4(-2x + 9) = 9

7x + 8x - 36 = 9

15x  = 45

Divide each side by 15.

x = 3.

Subsstitute x  value in (2).

y  = -6+9

y  = 3

Solution x  = 3, y  = 3.