Solve by substitution method:?

Question

Solve by substitution method:
3x - y = -15
y - x = 7

Answer 1

y= 7+x
3x-(7+x)= -15
3x-7-x= -15
2x= -8
x= -4
y-(-4)=7
y+4=7
y=3
(-4,3)

Answer 2

3x - y = -15 .............. (1)
y - x = 7
so y = 7 + x ............. (2)

Substitute equation (2) into equation (1)

Therefore 3x - (7 + x) = -15
2x - 7 = -15
2x = -8
x = -4
Substitute in equation (2)
y - -4 = 7
ie y + 4 = 7
So y = 3

Check in equation (2)
3x - y = 3 * (-4) - 3
= -12 - 3
= -15 ..... YESSSSSSSSSSSSSS!!!!!

So the solution is x = -4 y = 3

Answer 3

3x-y=-15 eq.1
y-x=7 eq.2

y=7+x eq.3

from equation 1 substitute the value of y taken from equation 2
3x-y=-15
3x-(7+x)=-15
3x-7-x= -15
3x-x-7= -15
2x=-15+7
2x=-8
x=-8/2
x=-4

from equation 3 substitute the value of x

y=7+x
y=7+(-4)
y=7-4
y=3

checking:
3x-y=-15
3(-4)-(3)=-15
-12-3=-15
-15=-15

Answer 4

3x - y = -15.....Eq 1
y - x = 7.....Eq 2
Consider Eq 2
y - x = 7
y = x + 7
Now substitute the derived value of 'y' in Eq 1
3x - y = -15
3x -(x + 7) = -15
3x - x - 7 = -15
2x - 7 = -15
2x = 7 - 15
2x = -8
x = -8/2
x = -4
Substitute the value of 'x' in Eq 2
y - x = 7
y -(-4) = 7
y + 4 = 7
y = 7-4
y = 3

Answer 5

Add x to both sides of the second equation to get:

y=x+7.

Then, instead of y, have (x+7), substitute it in to get:

3x-(x+7)=-15

Then remove the parenthesis (really distributing a -1)

3x-x-7=-15

Then, combine the like terms:

2x-7=-15

Then, add 7 to both sides to get:

2x=-8

Divide both sides by 2 to isolate the variable and you're left with:

x=-4

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Then, solve for y:

substitute in x=-4 in the second equation to find y:

y-(-4)=7

Remove double negative:

y+4=7

Subtract 4 from both sides to isolate y:

y=3

Hope this helps!!

Answer 6

take the easies question and rearrange it to solve for one variable. in this case i would take y - x = 7 and re arrange it to read y = x + 7. Now take that equation and substitute it into the other one where you see a y

3x - (x +7) = -15

3x - x= 2x, -15 - 7 = -22

so now your equation looks something like y = 2x - 22

now solve for x, then take either equation and solve for y, and then you have your answer

Answer 7

y-x=7
y=x+7

3x-(x+7)= -15
3x-x-7= -15
2x-7= -15
2x= -8
x= -4

y-(-4)=7
y+4=7
y=3