Question 376676
#4	
Equation 1:(3x – 4y = -30)
Equation 2:(7x + 4y = 10) 


Add the 2 equations, the y should cancel out.

 3x – 4y = -30
 7x + 4y =  10
10x + 0y = -20 <-- this simplifies to 10x = -20


From here, solve for x.
10x = -20
{{{(10/10)x = (-20/10)}}}
x = -2


Now substitute x with x = -2 in one of the 2 equations.
Equation 1:(3x – 4y = -30)

3x – 4y = -30
3(-2) – 4y = -30
-6 - 4y = -30
-4y = -24
y = 6



#5
Equation 1:(x – 4y = 29)
Equation 2:(3x + 2y = -11)


Multiply equation 1 by 3 so that the coefficient of x in both equations are the same.

x – 4y = 29
3x - 12y = 87 <-- Let this be equation 3.


Now subtract equation 3 from equation 2.
3x + 2y = -11
3x - 12y = 87
0x + 14y = -98 <-- This simplifies to 14y = -98


Solve for y.
14y = -98
{{{(14/14)y = (-98/14)}}}
y = -7


Substitute y for y = -7 in one of the 3 equations.
Equation 1:(x – 4y = 29)

x – 4y = 29
x – 4(-7) = 29
x + 28 = 29
x = 1


Now try to do #6 by yourself using this method. If you need help with #6 after you've tried it, just message me.