JAMB - Mathematics (1986 - No. 12)
In 1984, Ike was 24 yrs old and his father was 45 yrs old. In what year was Ike exactly half his father's age?
1981
1979
1982
1978
Vysvětlení
Let the no. of years be y
24 - y = \(\frac{1}{2}\)(45 - y)
45 - y = 2(24 - y)
45 - y = 48 - 2y
2y - y = 48 - 45
∴ y = 3
The exact year = 1984
1984 - 3 = 1981
24 - y = \(\frac{1}{2}\)(45 - y)
45 - y = 2(24 - y)
45 - y = 48 - 2y
2y - y = 48 - 45
∴ y = 3
The exact year = 1984
1984 - 3 = 1981