0.04(30h) is the part of the expression that represents the amount of tax she must pay. This part shows that 0.04 (4%) is the tax rate, 30 is the amount of money needed to pay per hour (h). Taxes are a percentage of the actual price added on to the actual price, so that means that 30h is the actual price, 30 dollars an hour, and 0.04(30h0 are the taxes she has to pay.
