Question

John is twice as old as Mary. The sum of their ages is 52. How old is Mary?

If J = John's age and M = Mary's age, which system of equations could be used to solve the problem?

2J = M and J + M = 52
J = 2M and J + M = 52
J = 2M and JM = 52

Answer 1

John =2M
M= M
So M+2M=52

2nd choice

Answer 2

J = 2M and J + M = 52

Explanation:

Let John's age be J

Let Mary's age be M

Now we are given that John is twice as old as Mary

So, John's age =
`J = 2M`

Now we are given that The sum of their ages is 52.

So,
`J+M=52`

Thus the system of equations could be used to solve the problem is
`J = 2M` and
`J+M=52`

Hence Option B is correct.