Question

Joan works on commission for a furniture store. She gets a base pay of $80 a day plus 4 percent of the value of any merchandise she sells that exceeds a total of $400. Joan wrote the expression 400 + 0.04(t − 80), where t represents her sales total in dollars, to compute the total amount of money that she will make. For sales of $575 Joan calculated that she will make $419.80. Explain Joan's error by completing the correct expression and how much she will make. I need the expression and how much she will make, please help! ! ! !

Answer 1

She gets a base pay of $80, so you must have a plain 80 in the expression.

80

Then she gets 4% of the value of merchandise she sells above $400. If she sells t dollars of merchandise, the amount that exceeds $400 is t - 400. For example, if she sold $500, then the amount that exceeds $400 is $100, and t - 400 = 500 - 400 = 100, so you see the expression t - 400 does give the amount of sales exceeding $400. She gets 4% of the amount that exceeds $400, so she gets 4%(t - 400) = 0.04(t - 400). Now we add this to the fixed 80 we had from above.

The correct expression is:

80 + 0.04(t - 400)

Joan's error is that she switched the 80 and the 400 in her formula.

Now we calculate her daily salary for sales of $575 in one day.

80 + 0.04(t - 400) =

= 80 + 0.04(575 - 400)

= 80 + 0.04(175)

= 80 + 7

= 87

She will make $87 for that day.

Answer 2

80 + (0.04 x t)

She will earn $103