3 books and 2 pens cost $8. 5 books and 3 pens cost $13.
find the total cost of one book and one pen.
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At the beginning of 1974/75,2 years a man invested #2000 in a bank at 12.5% compound interest, if it degree #650 at the end of each two years to pay his son's school fees, after payment of interest to pay his son's school fees, how much did he have left at the beginning of the 1978/79 school year?

Adam used 1072.4 gallons of water over the course of 7 days. how much water did adam use, on average, each day?