$\"\"$ $\"\"$

The equation is $\"\"$

According to addition property of equality:if $\"\"$ then $\"\"$ .

$\"\"$ (Add 20 to each side)

$\"\"$ (Apply additive inverse property: $\"\"$ )

$\"\"$ (Apply additive identity property: $\"\"$ )

$\"\"$ (Add: $\"\"$ ) $\"\"$

Check:

To check the solution, substitute $\"\"$ in original equation.

$\"\"$ (Substitute $\"\"$ )

$\"\"$ (Subtract: $\"\"$ )

Compare the values, the equation is true. The solution is $\"\"$ . $\"\"$

The value of $\"\"$ .