I really need help with this​

Which is an equation for the nth terms of the sequence 12,15,18,21

This figure consists of a rectangle and semicircle. what is the perimeter of this figure use 3.14 for pi 60.84m 72.84m 79.68m 98.52m

Acomputer store buys a computer system at a cost of $370.80. the selling price was first at $ 618, but then the store advertised a 20 % markdown on the system. answer parts a and b. a. find the current sale price.