Adam has 18 red marbles.
He has 6 times as many red marbles as blue marbles.
After he buys an equal number of red and blue marbles,
the number of red marbles is 2 times that of the blue marbles.
- How many red marbles are there in the end?
- How many blue marbles are there in the end?
- How many marbles are there in the end?
- How many marbles does Adam buy?
|
Red marbles |
Blue marbles |
Difference |
Before |
6 x 1 = 6 u |
1 x 1 = 1 u |
5 x 1 = 5 u |
Change |
+ ? |
+ ? |
|
After |
2 x 5 = 10 u |
1 x 5 = 5 u |
1 x 5 = 5 u |
(a)
The difference in the number between the red and blue marbles at first and in the end remains unchanged.
LCM of 5 and 1 is 5.
6 u = 18
1 u = 18 ÷ 6 = 3
Number of red marbles in the end
= 10 u
= 10 x 3
= 30
(b)
Number of blue marbles in the end
= 5 u
= 5 x 3
= 15
(c)
Total number of marbles in the end
= 30 + 15
= 45
(d)
Total number of marbles that Adam buys
= (10 u - 6 u) x 2
= 4 u x 2
= 8 u
= 8 x 3
= 24
Answer(s): (a) 30; (b) 15; (c) 45; (d) 24