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