Antonio and Derek shared 60 apples. Antonio had twice as many apples as Derek. When Derek gave some apples to Antonio, he had four times as many apples as Derek.
(a) How many apples did Derek have at first?
(b) How many apples did Derek gave Antonio?
(a) Let a = number of initial apples Antonio had.
Let b = number of initial apples Derek had.
a+b=60 (1)
a=2b (2)
(2) substituted into (1) => 3b = 60
b = 20.
20 apples.
Thus Derek had 20 and Antonio had 40.
(b) Let c = number of apples Derek gave Antonio
(40+c) = 4(20-c) (3)
40+c = 80 - 4c
5c = 40
C = 8 apples
Derek gave 8 apples to Antonio.