Nine simple 9th grade math questions

Acyclist bike x distance at 10 miles per hour .and returns over the same path at 8 miles per hour. what is the cyclist average rate for the round trip in miles per hour ?

Which of the following equations is equivalent to x/3-6/x=1

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?