Answer:
Step-by-step explanation:
2x - 3y = 9
-5x - 3y = 30
For simplicity, let's eliminate the y variable in this system by multiplying the second equation by -1:
-1·(-5x - 3y = 30)
==> -1·-5x - -1·3y = -1·30
==> 5x + 3y = -30
Add this equation to the first original equation:
2x - 3y = 9
+ 5x + 3y = -30
__________________
2x + 5x - 3y + 3y = 9 + -30 ==> 7x + 0y = -21 ==> 7x = -21
7x = -21
7x/7 = -21/7 ==> x = -3
Plug this value for x into either of the original equations from the system (I will use the first equation) to solve for y:
2x - 3y = 9
2·(-3) - 3y = 9
-6 - 3y = 9
Add 6 to both sides of the equation:
-6 + 6 - 3y = 9 + 6
-3y = 15
Divide both sides of the equation by -3:
-/-3 = 15/-3
y = -5
