If I was 7 when my sister was 16 and my brother was 8 when she is 19 how many more years will it take my brother to reach 21 when I'm 13?
10 more years, the I character is 9 years uounger than his sister while the brother character is 11 years younger than the same person therefore they are two years apart the I character being older 13-2=11 21-11=10