Question

the ages of John and Mary total 27 years. Mary's age plus twice john's age is 40. how old is each person?

Answer 1

`J+M=27`

`2J+M=40`


`J=27-M`


`2(27-M)+M=40`

`54-2M+M=40`

`54-M=40`

`-M=-14`

`M=14`


`2J+14=40`

`2J=26`

`J=13`

John is 13 years old
Mary is 14 years old

Answer 2

so
Jon's age=j
mary age=m


m+j=27
m+2 times j=40
m+2j=40
M+j=27
ssubtract j from both sides
m=27-j
subsitute 27-j for m
27-j+2j=40
27+j=40
subtract 27 fromboth sdies
j=13

subsitue
13+m=27
subtract 13
m=14

mary=14
john=13