Solve the quadratic equation x^2+9x-15=0

Gretchen is setting up for a banquet. she has 300 chairs and needs to distribute them evenly among t tables. how many chairs should she put at each table? write your answer as an expression.

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?

Sally deposited money into a savings account paying 4% simple interest per year. the first year, she earn $75 in interest. how much interest will she earn during the following year?