Question

You order two tacos and a salad. The salad costs $2.50. You pay 8% sales tax and leave a $3 tip. You pay a total of $13.80. How much does one taco cost?

Answer 1

Price of one taco = x; price of 2 tacos = 2xPrice of salad = $2.50Sales tax = 8% of the combined price of two tacos and a salad, namely .08(2x + 2.50)Tip = constant fee = $3.00Total bill = $13.80 Therefore the equation becomes

2x + 2.50 + .08(2x + 2.50) + 3 = 13.80 Step 3:  Solve for x; isolate the variable 2x + 2.50 + .16x + .20 + 3 = 13.80 (using the distributive property to multiply 2x and 2.5 by .08).2.16x + 2.70 + 3 = 13.80 (combining like terms)2.16x + 5.70 = 13.80 (combining like terms)2.16x + 5.70 = 13.80 - 5.70 (subtraction property of equality)2.16x = 8.10x = 8.10/2.16 = 3.75 (division property of equality) Step 4: Interpret mathematical answer in context of original word problem. The cost of a single taco is $3.75 Step 5: Verify that answer makes sense for problem. 2 Tacos would cost $7.501 Salad would cost $2.50Food bill subtotal would be $10.00Sales tax is 8% of $10 or 80 centsTip is $3 Confirm 7.5 + 2.5 + .8 + 3 = $13.80