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? y = x + 5 and y + 10 = 2x y = x + 5 and 2(y + + 10) = 35 y = x + 5 and 2(y + 10) = x