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Suppose the younger brother's age is x and the older brother's age is 5x.

Three years later, my brother's age is x+3, and my brother's age is 5x+3.

(5x+3)=3(x+3)。 When solving this equation, x=3, that is, my brother is 3 years old and my brother 15 years old.

You can also think of it this way: the younger brother's age after three years is +3, and the older brother's age after three years is 5 times +3.

Three years later, my brother is three times as old as my brother. Subtract three times from five times, the original age is still two times, and three times when my brother is three years old is exactly equal to the remaining two times+three, so there is

(3*3-3)/2=3 (years old) is my brother's present age, and my brother is 3*5= 15 years old.

2. The age gap between Party A and Party B is affirmative. When Party A is the same age as Party B, it is the age difference compared with 4 years old, but it is the age difference from Party B to Party A, and it is the age difference from Party A to 58 years old, so the age difference from 4 years old to 58 years old is three times that of Party A and Party B, so there are

(58-4)/3= 18, so B =4+ 18=22 years old and A =22+ 18=40 years old.