Question

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

Answer 1

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

2nd choice

Answer 2

Answer:

J = 2M and J + M = 52

Step-by-step 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.