Сколько процентов составляют: а) 42 км от 120 км; 6)36 от 45; в) 45 от 36; г) х от у?

The phone is useful, it is necessary to call his family and loved ones,to report the news,and much more at very high speeds, letters such alas you can't, the phone is a negative thing and positive, it depends which way you look