3x+7=5x-21 Find the value of x

Since 5x contains the variable to solve for move it to the left-hand side of the equation by subtracting 5x from both sides.
3x+7−5x=−21

Add 3x and −5x to get −2x.
−2x+7=−21

Since 7 does not have the variable to solve for, move it to the right hand side of the equation by subtracting 7 from both sides.
−2x=−7−21

Subtract 21 from −7 to get −28.
−2x=−28

Divide each term in the equation by −2.
x=14


x=14