Answer:
Step-by-step explanation:
1. x+y=14 ; y=x+4
substitute:
x+x+4=14 ; combine like terms and transpose the constant
2x=14-4 (sign changes when moving one term to the other side)
2x=10 divide both sides by 2 to isolate/get x
x=5
Then apply x as 5
5+y=14 transpose
y=9
2. y=x-7 ; x+y=15
solve for 1 variable
x+y=15 ; transpose
x=-y+15
Then
substitute:
y=-y+15-7 ; transpose
2y=8 divide both sides by 2 to get y
y=4
Then apply y as 4
4=x-7 transpose
x=11
3. y=x-10 ; x+2y=4
solve for one variable:
x+2y=4 transpose
x=-2y+4
Substitute:
y=-2y+4-10 ; solve then transpose
3y= -6 divide both sides by 3 to get y
y=-2
Then apply y as -2
-2=x-10 transpose
10-2=x
x=8
