Answer:
The expression to calculate her pay should be 80+0.05(t-400)
That is assuming her 5% of the difference. The formula is her base pay (80) added to the 5% of the merchandise over 400.
The answer I got using the new formula, using 475 for t:
80+0.05(475-400) = Total pay
80+3.75= Total pay
$83.75 is her total pay that day.
Explanation: