Question

Solve for x and y:

7y−5x=31

x=4−2y

Select one:
a. x=8,y=−2
b. x=−2,y=3
c. x=−9,y=−2
d. x=3,y=−2

Answer 1

This is a system of equation:

7y - 5x = 31

x = 4 - 2y

Plug in 4 - 2y for x

7y - 5(4 - 2y) = 31

Distribute -5 to both 4 and -2y

7y - 20 + 10y = 31

Simplify

17y - 20 = 31

Isolate the y. Note the equal sign. What you do to one side you do to the other. Do the opposite of PEMDAS.

Add 20 to both sides

17y - 20 (+20) = 31 (+20)

17y = 51

Divide 17 from both sides to isolate the y

17y/17 = 51/17

y = 51/17 or 3

y = 3

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Plug in 3 for y in one of the equations.

x=4−2y

x = 4 - 2(3)

Simplify.

x = 4 - 6

x = -2

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x = -2, y = 3 is your answer, or B)

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hope this helps