1. A kilogram of roast beef currently costs $105. If the increase in the price per kilogram of meat will be $1.5 each month, how many months from now will a kilogram of roast beef cost $130.50?
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3. Mr. Buenavida receives a salary of $11,111.11 each month. If he spends 27% on rent and 43.2% on food, how much does he have available for other expenses?
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5. Elmer Homer is solicited by two companies; the first offers him a starting salary of $12,400 per month with monthly raises of $290 for one year. The second offers him a starting salary of $13,500 per month and monthly raises of $150 for one year. If you consider the way a worker receives his salary in Mexico which is monthly pay, which company is more convenient for you? 
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7. A company buys a machine for $95,000. The machine depreciates each year, so that its value after n years is given by the equation: V=95,000 (0.85)^n. You are asked to determine the value of the machine in 5 years.
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9. In a laboratory they found 10,000 bacteria in a culture and their size was increasing 1.15 times every hour. a) How many bacteria will there be in 24 hours?
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11.  When purchasing a machine on credit, a company must pay $20 000 at the end of the first month, $22 400 at the end of the second month, $25 088 at the end of the third month, and so on. How much is paid for the machine if 12 payments are made in total?
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13. Marisela bought a new package car for $180,000. If it depreciates in value by 20% each year, in how long will her car be worth $30,200?
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15. A school's revenue is determined by multiplying the number of students by the tuition for each student. Each year the number of students increases by 650. In 2015 it had a total of 4,630 students. On the other hand, the tuition they pay increases by $500 per student each year, in 2016 each student was charged $6,500, how much will the school receive in total tuition in the year 2024?