Exercise 4 Page 181

We want to find how much a customer paid in total at a restaurant. Let's start by calculating the dollar amount of the sales tax by using the percent equation. part = percent * whole We are given that the bill comes to $ 42.75 and the sales tax is 6 %. Let s represent the dollar amount of the sales tax. s = 6 % * $ 42.75 We need to write the percent as a decimal before we can solve the equation that we created. We can do this by ignoring the percent symbol and moving the decimal point two places to the left.

Therefore, 6 % is equal to 0.06. s = 6 % * $ 42.75 [0.3em] ⇓ [0.3em] s = 0.06 * $ 42.75 Now let's solve the equation for s. For simplicity, we will ignore the units for now.

We got that s≈ 2.57 is a solution to the equation. This means that the dollar amount of the sales tax is about $ 2.57. Now we can calculate the bill after tax. $42.75 + $ 2.57 = $ 45.32 The bill after tax is $ 45.32. Next, we are told that a 15 % tip is left on the amount after the tax is added. We can use the percent equation again to find the dollar amount of the tip. Let t represent the dollar amount of the tip. part = percent * whole ⇓ t = 15 % * $ 45.32 Let's rewrite the percent as a decimal. t = 15 % * $ 45.32 [0.3em] ⇓ [0.3em] t = 0.15 * $ 45.32 Now we can solve the equation for t.

We got that the dollar amount of the tip is about $ 6.80. Finally, we will calculate how much the customer paid in total. $45.32 + $ 6.80 = $ 52.12 The customer paid about $ 52.12 in total.