Question

Having a problem figuring out how to solve these types of math problems, any help would be appreciated. Use substitution to solve the system
The explanations provide in ALEKS does not make sense to me.

-3x + y = -11
2X + 5y = 30

Answer 1

1) -3x + y= -11
2)2x + 5y = 30

Either both x or both y have to be equal
So 1) can be multiplied by 5 to get y to become 5y

Therefore 1) becomes 3) -15x + 5y = 30


So you do 2) - 3)

To get 17x=85
Divide both sides by 17 to get x=5



Then to get y sub 5 into 2x + 5y= 30


2*5 + 5y = 30

10 + 5y = 30

-10. -10

5y = 20

/5. /5


Y= 4




So you get that y=4 and x=5

Answer 2

The two equations can be solve using substitution method. 
-3x + y = -11    .....................(1)
2X + 5y = 30    .....................(2)

From equation 1,
-3x + y = -11 
y=-11+3x
y=3x-11

Substitute the vale of y in equation 2 with y=3x-11,
2X + 5y = 30
2x + 5(3x-11) = 30
2x + 15x - 55 = 30
17x -55 = 30
17x = 30+55
17x = 85
x =85/17
   =  5

From the equation 1, 
 y=3x-11
Since  x = 5,

y = 3(5) - 11
  = 15 - 11
  = 4

Answer;
     x = 5
     y = 4