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Lisa has three classes that each last 50 minutes. what is the total number of minutes of the three classes

When using the linear combination metho e linear combination method to solve a system of linear equations, the four options are:

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?