Question

PLEASE HELP FAST!!!!!

Answer 1

The solution of the system of equations be:

`x=8,\:y=4`

Hence, option C is true.

Explanation:

Given the system of equations

`\begin{bmatrix}4x+7y=60\\ -4x+7y=-4\end{bmatrix}`

adding both the equations

`-4x+7y=-4`

`+`

`\underline{4x+7y=60}`

`14y=56`

so the system of equations becomes

`\begin{bmatrix}4x+7y=60\\ 14y=56\end{bmatrix}`

solve 14y for y

`14y=56`

Divide both sides by 14

`(14y)/(14)=(56)/(14)`

Simplify

`y=4`

`\mathrm{For\:}4x+7y=60\mathrm{\:plug\:in\:}y=4`

`4x+7\cdot \:4=60`

`4x+28=60`

Subtract 28 from both sides

`4x+28-28=60-28`

Simplify

`4x=32`

Divide both sides by 4

`(4x)/(4)=(32)/(4)`

`x=8`

Therefore, the solution of the system of equations be:

`x=8,\:y=4`

Hence, option C is true.