Question

HELP PLEAAASSSEEE!!!!

​ solve the system of equations
7x−3y=20

y=5x−4
​
x=

y=

Answer 1

x = - 1, y = - 9

Explanation:

Given the 2 equations

7x - 3y = 20 → (1)

y = 5x - 4 → (2)

Substitute y = 5x - 4 into (1)

7x - 3(5x - 4) = 20

7x - 15x + 12 = 20

- 8x + 12 = 20 ( subtract 12 from both sides )

- 8x = 8 ( divide both sides by - 8 )

x = - 1

Substitute x = - 1 into (2) for corresponding value of y

y = (5 × - 1) - 4 = - 5 - 4 = - 9

Solution is (- 1, - 9)

Answer 2

x=-1 and y=-9

Explanation:

So the equations are 7x-3y=20 and y=5x-4

the second equation gives you a value that you can substitute in for y

sub for y in the first equation:

7x-3(5x-4)=20

distribute the 3 to the values in the parenthesis

7x-15x+12=20

combine like terms

-8x+12=20

subtract 12 from both sides

-8x=8

divide both sides by -8

x=-1

Now that you have your x value you should sub it into one of the equations to get the y value, we will sub it into the first equation

7(-1)-3y=20

multiply

-7-3y=20

add 7 to both sides

-3y=27

divide both sides by -3

y=-9

Substitute the values in to check your work

7(-1)-3(-9)=20

-7+27=20

20=20

correct, now the other equation

(-9)=5(-1)-4

-9=-5-4

-9=-9

correct