#18 please help me solve this

x = -1

y = 1

Step-by-step explanation:

The system of equation is:

-7x + 2y = 9 ⇒ (1)

-4x - 7y = -3 ⇒ (2)

To solve the system multiply equation (1) by 7 and equation (2) by 2 to make the coefficients of y equal in values and different in signs, then add the two resulting equations to eliminate y and solve the new equation for x to find its value

∵ 7(-7x) + 7(2y) = 7(9)

∴ -49x + 14y = 63 ⇒ (3)

∵ 2(-4x) - 2(7y) = 2(-3)

∴ -8x - 14y = -6 ⇒ (4)

- Add equations (3) and (4)

∴ -57x = 57

- divide both sides by -57

∴ x = -1

Substitute the value of x in equation (1) or (2) to find y

∵ -7(-1) + 2y = 9

∴ 7 + 2y = 9

- Subtract 7 from both sides

∴ 2y = 2

- Divide both sides by 2

∴ y = 1

c. side angle side. u shares the same sides