A saleswoman received $40 per day, plus a commission of 2% on all sales over $300 per week. What was her salary for a 5-day week during which her sales amounted to $1260?

2 % = 2/100 = 0.02

So her salary is broken down into two parts.

The systematic part is $40 per day for 5 days, so 40*5.

The changing part is 2% of weekly sales over 300, so 0.02 (1260-300).

Salary = 5*40 + 0.02 (1260-300) = $219.20