John is 5 years older than mary. in 10 years, twice john's age decreased by mary's age is 35, and john's age will be twice mary's current age. find their ages now. if x is mary's age now and y is john's age now, which system of equations could not be used to solve the problem?
1. y = x + 5 and y + 10 = 2x
2. y = x + 5 and 2(y + + 10) = 35
3. y = x + 5 and 2(y + 10) = x

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.