116 Chapter 1 Linear Equations and Inequalities in One Variable Section 1.2 Applications of Linear Equations in One Variable Key Concepts Problem-Solving Steps for Word Problems 1. Read the problem carefully. 2. Assign labels to unknown quantities. 3. Write a verbal model. 4. Write a mathematical equation. 5. Solve the equation. 6. Interpret the results and write the final answer in words. Sales tax: (cost of merchandise)(tax rate) Commission: (dollars in sales)(commission rate) Simple interest: I Prt Distance (rate)(time) d rt Examples Example 1 1. Estella needs to borrow $8500. She borrows part of the money from a friend and agrees to pay the friend 6% simple interest. She borrows the rest of the money from a bank that charges 10% simple interest. If she pays back the money at the end of 1 yr and also pays $750 in interest, find the amount that Estella borrowed from each source. 2. Let x represent the amount borrowed at 6%.Then 8500 x is the amount borrowed at 10%. 3. 4. 5. 6. Principal x 8500 x 8500 Interest 0.06x 0.10(8500 x) 750 a Interest owed at 6% 6% Account 10% Account Total b a interest owed at 10% 0.06x 0.1018500 x2 750 6x 1018500 x2 75,000 6x 85,000 10x 75,000 x 2500 4x 10,000 x 2500 8500 2500 6000 b a total interest b $2500 was borrowed at 6% and $6000 was borrowed at 10%.
miller_intermediate_algebra_4e_ch1_3
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