The answer is -9/8, hope this helps!
X + y = 1
add - y both sides
x + y + - y = 1 + - y
x = - y + 1
Answer: x = - y + 1
Graph: y = - x + 1
x + 7y = - 4
add - 7 both sides
x + 7y + - 7y = - 4 + -7y
x = - 7y - 4
Answer: x = - 7y - 4
Graph: y = 0.142857x - 0.571429
2x - 6y = 4
add 6y to both sides
2x - 6y + 6y = 4 + 6y
2x = 6y + 4
divide both sides by 2
2x/2 = 6y + 4/2
x = 3y + 2
Answer: x = 3y + 2
Graph: y = 0.333333x - 0.666667
5x + 15y = - 10
add - 15 to both sides
5x + 15y + - 15y = - 10 + - 15y
5x = - 15y - 10
divide both sides by 5
5x/5 = - 15y - 10/5
x = - 3y - 2
Answer: x = - 3y - 2
Graph: y = - 0.333333x - 0.666667
2x + 6y = 10
add - 6y to both sides
2x + 6y + - 6y = 10 + - 6y
2x = - 6y + 10
divide both sides by 2
2x/2 = - 6y + 10/2
x = - 3y + 5
Answer: x = -3y + 5
Graph: y = - 0.333333x + 1.666667
Hope that helps!!!
Use substitution.
2p + 3(2p) = 680
2p + 6p = 680
8p = 680
p = 85
Plug in.
x = 2p
x = 2(85)
x = 170
p = 85
