Acommuter has $245 in his computer savings account. this account changes by -$15 each week he buys a ticket. in one time period, the account changed by -$240. for how many weeks did the commuter buy tickets? how much must he add to his account if he wants to have 20 weeks worth of tickets in his account?

Adecibel is a logarithmic unit that can be used to measure the intensity of a sound. the function y = 10logx gives the intensity of a sound in decibels, where x is the ratio of the intensity of the sound to a reference intensity. the reference intensity is generally set at the threshold of hearing. use the graphing utility to graph the decibel function.a whisper has a sound intensity of 30 decibels. use your graph to you complete the following statement. the sound intensity of a whisper is times the reference intensity.