Convert the statement Adding 15 to 4 times x is 39 into an equation _________. A family spent Rs. 52.00 for circus tickets. This cost included a Rs. 3.25 service fee for the order, with the cost of the circus tickets being Rs. 9.75 each. How many tickets did the family buy? Justify your answer. Understand the problem The answer is the number of tickets that family bought. List the important information– The service fee is Rs. 3.25 per order, the tickets cost Rs. 9.75 each, and the total cost is Rs. 52. Let t represent the number of tickets bought. Total cost = Tickets + Service Fee 52.00 = 9.75t + 3.25 Make a Plan Think: First the variable is multiplied by 9.75, and then 3.25 is added to the result. Work backward to solve the equation. Undo the operations in reverse order. First subtract 3.25 from both sides of the equation and then divide sides of the new equation by 9.75. Solve 52.00 = 9.75t + 3.25 –3.25 –3.25 Subtract 3.25 from both sides. 48.75 = 9.75t 48.75 9.75t = Divide both sides by 9.75. 9.75 9.75 5=t The family bought 5 tickets. Look Back You can use a table to decide whether your answer is reasonable. Five tickets is a reasonable answer. Tickets Cost of Tickets Service charge Total cost 1 Rs. 9.75 Rs. 3.25 Rs. 13.00 2 Rs. 19.50 Rs. 3.25 Rs. 22.75 3 Rs. 29.25 Rs. 3.25 Rs. 32.50 4 Rs. 39.00 Rs. 3.25 Rs. 42.25 5 Rs. 48.75 Rs. 3.25 Rs. 52.00 Sometimes, a two-step equation contains a term or an expression with a denominator. In these cases, it is often easier to first multiply both sides of the equation by the denominator in order to remove it, and then work to isolate the variable.
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4x + 15 = 39