What's the unit rate for 42 laps in 6 races?

The sum of two numbers is 86, and their difference is 20. find the two numbers

Ill mark the brainliest if you me with the these three questions 7,8,9

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?