Ascrewdriver cost $99, if you save $79 what is the percent of change?

To calculate the percentage of change We:
⇒work out the difference of the two costs
                               $99-$79=$20
⇒Divide the difference by the original
                                
⇒Multiply by 100 to get the answer as a percentage
                           × 100
                           =20.2%
When we have a check:
$99 × 0.202 = 19.998 ≈ $20
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                              The right answer