Question 498115: Janis is 3 years older than her sister. Thirty years from now the sum of their ages will be 111. Find the current ages of the sisters. Answer by Maths68(1474) (Show Source):
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Present age of Janis = j
Present age of sister = s
Janis is 3 years older means if we add 3 to the sister age both girls will be of same age
j=s+3 ............(1)
Thirty years from now means we have to add 30 in their present ages then sum them up
(j+30)+(s+30)=111
j+30+s+30=111
j+s+60=111
j+s=111-60
j+s=51 ...........(2)
Plug in the value of j from (1) to (2)
(s+3)+s=51
s+3+s=51
2s+3=51
2s=51-3
2s=48
Divide by 2 both sides of the equation
2s/2=48/2
s=24
Plug in the value of s in (1)
j=s+3
j=24+3
j=27
Present age of Janis = 27
Present age of sister = 24
