5(x+2)=7(4-x)

What is x?

Option C is correct.

Multiply the first equation by -7 to get;    -28x - 7y = -28.

Step-by-step explanation:

Given the system of equation:

                       .....[1]

                  .....[2]

Multiply equation [1] by -7 to both sides we get;

Using distributive property;

                      ......[3]

Combined the equation [2] and [3] , the variable y will be eliminated to solve for x.

Therefore, the following actions create an equivalent system  such that, when combined with the other equation, one of the variables is eliminated is;

Multiply the first equation by -7 to get;    -28x - 7y = -28