John is four times as old as Martha. Five years ago the sum of their ages was 50. How old are they now?

John is 48 and Martha is 12

Step-by-step explanation:

John is four times as old as Martha or:

John = 4 * Martha

j=4m

Five years ago the sum of their ages was 50 or:

John - 5 + Martha - 5 = 50

j-5+m-5=50

j+m=60

Substitute Martha for John

4m+m=60

5m=60

m=12

Martha is 12

Substitute 12 for Martha

j+12=60

j=48

John is 48

We can double check this by checking that John is 4 times as old as Martha and that 5 years ago the sum of their ages was 50.

12*4=48

48=48

12-5+48-5=50

7+43=50

50=50