Which explicit formula describes the sequence {87, 83.4, 79.8, 76.2, …}?

Write an algebraic expression to match each statement a. four less than 8 times a number b. twice the difference of a number and six c. nine from a number squared

Is there an x intercept in the equation 60*1.15^x

Simplify. 3(4+4x) (type your answer in with no spaces)