Algebra problem solving

Question

a boy is 5 years older than his sister in 15 years the sum of their ages will be 61. what is the age of each

 

thanks

Answer 1

y=x+5

(x+15) +(y+15)=61

x+y+30=61

x+y=31

x+(x+5)=31

2x=31-5=26

x=13

y=18

15 yrs later: 13+15=28 & 18+15=33...33+28=61