Question

PLEASE HELP FAST!!!!!

Answer 1

Answer:

The solution of the system of equations be:

$x=8,\:y=4$

Hence, option C is true.

Step-by-step 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

$\frac{14y}{14}=\frac{56}{14}$

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

$\frac{4x}{4}=\frac{32}{4}$

$x=8$

Therefore, the solution of the system of equations be:

$x=8,\:y=4$

Hence, option C is true.