The sum of the ages of john and mary is 32. four years ago, john was twice as old as mary . find the present age of each

John is  

20

Mary  

12

Step-by-step explanation:

We can use one variable to define their ages because we know the relationship between their ages.

Mary is younger, let Mary's present age be  

x

years,

Then John's present age is  

32

−

x

years (Sum of their ages is  

32

)

4

years ago, they were both  

4

years younger than now.

Mary was  

(

x

−

4

)

and John was  

(

32

−

x

−

4

)

=

(

28

−

x

)

years old.

John was twice as old as Mary:

2

(

x

−

4

)

=

28

−

x

2

x

−

8

=

28

−

x

3

x

=

28

+

8

3

x

=

36

x

=

12

Mary's age is  

12

and John's age is  

20

-12 > a

step-by-step explanation:

-11 > 1 + a

subtract 1 from each side

-11-1 > 1-1+a

-12 > a