X − 4y = 7
5x + 9y = 6
5x − 20y = 35 //1st * 5
5x + 9y = 6
5x +9y - 5x + 20y = 6 - 35 //2nd - 1st
5x + 9y = 6
29y=-29
5x=6-9y
y=-1 //1st : 29
5x=6-9*(-1)
y=-1
x=15:5 //2nd : 5
y=-1
x=3
check:
for x=3 and y=-1 there is:
x − 4y = 7 is 3 − 4*(-1) = 7 is 7=7 ok
5x + 9y = 6 is 15-9=6 is 6=6 ok
answer: (3;-1) represents the solution.
Answer:
its D
Step-by-step explanation:
Car travelling to the east is at 104 miles per hour and the car travelling to the west is moving at 114 miles per hour
