How can the numbers 3,2,4 and 1 equal the number 13 only using addition and subtraction?

Write the following as a base and exponent

Which number completes the inequality? 2/3 < _ < 7/9

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?