Answer:
The increase is $90 - $80 = $10.
Explanation:
To find the percent of increase, we start by finding the amount of increase as a fraction or proportion of the original amount. In this case, the amount of increase is:
$10 / $80 = 0.125
To convert this to a percentage, we multiply by 100:
0.125 × 100 = 12.5%
Therefore, Peter's salary increase represents a 12.5% increase from last week's salary.
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