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Solve the system of equations using the elimination method.

8x + 7y = 89
2x + 5y = 45

1 Answer

3 votes

Answer:

x=5

y=7

Explanation:

8x + 7y = 89 Equation 1

2x + 5y = 45 Equation 2

Multiply equation 1 with 2 (the coefficient of x in equation 2) and multiply equation 2 with 8 (the coefficient of x in equation 1). This will make x have to same coefficient in equation 3 and equation 4

2(8x + 7y = 89)

16x+14y=178 Equation 3

8(2x + 5y = 45)

16x+40y=360 Equation 4

Now that x have the same coefficient in equation 3 and equation 4, we subtract equation 3 from equation 4 to eliminate x

16x+14y=178 Equation 3

16x+40y=360 Equation 4

16x-16x=0

40y-14y=26y

360-178=182

26y=182

Divide both sides by 26

y=182/26

y=7

Substitute y for 7 in equation 2

2x + 5y = 45

2x+5(7)=45

2x+35=45

Make 2x the subject

2x=45-35

2x=10

Divide both sides by 2

x=10/2

x=5

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