>>...two sons, one of whom is twice old as the other.<< So: x = younger son's age now 2x = older son's age now. >>...A man's age is three times the sum of the ages of his two sons...<< So: man's age now =s 3(x + 2x), which =s 3(3x) which =s 9x >>...In four years...<< Younger sons' age in 4 years will be x+4 Older son's age in 4 years will be 2x+4 Man's age in 4 years will be 9x+4 >>...the sum of the son's ages (in four years)...<< So, sum of ages =s x+4 + 2x+4 =s 3x+8 <--sum of sons ages in 4 years. >>...will be half of their father's age. So, 3x+8 =(9x+4) Solve that for x, which will be the younger son's age. Multiply by 2 to get the older son's age. Add them and multiply by 3 to get the man's age. Edwin