I got an answer but it seems too complicated to be correct. Please help!

Frank has a devised a formula for his catering business that calculates the number of meatballs he needs to prepare. the formula is m=4a+2c, where c=number of children; m=number of meatballs; a=number of adults. how many meatballs are required for a party of 10 adults and 5 children?

Find the rate of change for the situation.you run 7 miles in one hour and 21 miles in three hours.

Explain how you can show five less than a number using algebraic expression