Do you know how do this because i need ?

X+ y = 5 ; x - y =3 solve using linear combination

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.

Gabrielle's age is two times mikhail's age. the sum of their ages is 84. what is mikhail's age?