Which of the following ordered pairs represents the solution to the system given below?

x - 4y = 7

5x + 9y = 6

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.