Respuesta :

Kaikerscupcake
Hey there! :D

Add the expression's together. 

3x+y=27

-3x+4y= -42

3x+(-3x)= 0

y+4y=5y

27+(-42)= -15

5y=-15

Divide both sides by 5. 

y=-3

Now, find x.

3x+y=27

3x-3= 27

3x=30

x=10

The solution is (10,-3). 

I hope this helps!
~kaikers
3x + y = 27 
-3x + 4y = -42

5y = -15
y = -3


3x + (-3) = 27
3x = 30
x = 10
answer is D