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

The expression is $\"\"$ .

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

$\"\"$ (Subtract 90 from each side)

$\"\"$ (Additive inverse property: $\"\"$ )

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

Check:

To check the solution Substitute the value of $\"\"$ in above expression.

$\"\"$

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

The value of $\"\"$

By the number line $\"\"$ $\"number$