Rick bought 3 shirts for $18 each, 2 pair of socks for $3.99 a pair, and a pair of slacks for $45.00. The sales tax rate is 8.5%. How much did he pay? and how did you find it?

For a short time after a wave is created by wind , the height of the wave can be modeled using y= a sin 2pi(t) / t where a is the amplitude and t is the period of the wave in seconds. how many times over the first 5 seconds does the graph predict the wave to be 2 feet high?