COURSE 2 LESSON 2 7 Write an Equation

COURSE 2 LESSON 2 -7 Write an Equation (For help, go to Lesson 2 -3. ) Write and solve an equation for each sentence. 1. Seven fewer than a number is 12. 2. The sum of 9 and a number is equal to 36. 3. Twenty-seven is 10 less than a number. 4. Seventeen more than a number is 5. 2 -7

COURSE 2 LESSON 2 -7 Write an Equation Solutions 1. n – 7 = 12 2. n – 7 + 7 = 12 + 7 9 + n = 36 9 – 9 + n = 36 – 9 n = 19 n = 27 3. 27 = n – 10; n = 27 + 10 = 37 2 -7 4. n + 17 = 5; n = 5 – 17 = – 12

COURSE 2 LESSON 2 -7 Write an Equation Of the 64 students going to the science fair, 36 will ride in a bus. The others will ride in vans that each carry 6 students. How many vans are needed? 36 of the 64 students going to the science fair will ride in a bus. The rest of the students will ride in vans that can carry 6 students each. You need to find the number of vans that are needed. There are two groups of students going to the science fair: those riding in a bus, and those riding in vans. The sum of the two groups cannot be less than the total number of students. Write an equation and solve the problem. 2 -7

COURSE 2 LESSON 2 -7 Write an Equation (continued) Words students plus students in the in each bus van Let Equation 36 v times number equals of vans total students = the number of vans needed. + 6 • v = 36 + 6 v = 64 Solve the equation. 36 – 36 + 6 v = 64 – 36 Subtract 36 from each side. 6 v = 28 or v = 4. 6 Simplify. Since you cannot have 4. 6 vans, 5 vans are needed. 2 -7 64

COURSE 2 LESSON 2 -7 Write an Equation (continued) Each van will carry 6 students. The total number of students able to ride in the vans and the bus is 36 + 5 • 6, or 66 students. If 4 vans are used, the total is 36 + 4 • 6, or 60 students. Since this is less than the total students traveling, the answer checks. 2 -7

COURSE 2 LESSON 2 -7 Write an Equation Lindsey has saved $12 to go to the movies. This is $3 more than twice the cost of a movie. What is the cost of a movie? Think about the information and what you are being asked to find. Lindsey has $12, and this is $3 more than twice the cost of a movie. You are asked to find the cost of a movie. Since you are given the relationship between the numbers, an equation can help you solve the problem. 2 -7

COURSE 2 LESSON 2 -7 Write an Equation (continued) Words two times Let Equation 2 c cost of a movie plus three equals total amount of money = the cost of a movie. • c + 3 = 2 c + 3 = 12 2 c + 3 – 3 = 12 – 3 Subtract 3 from each side. 2 c = 9 Simplify. 9 2 c = 2 2 Divide each side by 2. c = 4. 5 Simplify. The cost of a movie is $4. 50. 2 -7 12

COURSE 2 LESSON 2 -7 Write an Equation (continued) To check the solution, use 4. 5 for the cost of a movie. Since 2 • 4. 5 + 3 = 9 + 3 = 12, the answer is correct. 2 -7

COURSE 2 LESSON 2 -7 Write an Equation Solve each problem by writing and solving an equation. 1. Ravi bought 3 identical shirts and paid a sales tax of $2. 84. The total cost was $50. 18. What was the cost of each shirt? 3 s + 2. 84 = $50. 18; $15. 78 2. In 1976, Jimmy Carter received 58 fewer electoral votes than 5 times the number received by John Adams in 1796. Carter received 297 electoral votes. How many did Adams receive? 5 h = 297 + 58; 71 votes 2 -7