1. Write a system of equations to model each of the following situations. You do not need to solve the systems. a. One website charges $0.99 per song download. Another website charges a one-time user fee of $12, but only charges $0.89 per song download.
b. Sean operates a lawn cutting business. He charges $15 for a single lawn and $25 for a front and back lawn. Sean made $475 from 25 customers
c. Brass is an alloy made by melting and mixing copper and zinc. A metallurgist has two brass alloys, one that is 65% copper and one that is 90% copper. He would like to combine a portion of each alloy to produce 500 g of a new alloy that is 75% copper.
2. Solve the following systems of equations by elimination. Verify the solutions.
a. r + 2s + 1 = 0 and r + 5s +28 = 0
b. 4m - 3n = 27 and 8m - 6n = 18
c. 0.6x = 1.2 + 0.3y and 2.2x - 1.8y - 1.6 = 0
3. Frank has $8000 that he plans to split into two investments. He wrote the following two equations to represent the interest he will earn from each of the two investment options.
~ 2000A + 6000B = 520
~ 4000A + 4000B = 480
a. Determine the interest rates, A and B, as percentages.