Adam has 105 blue marbles.
He has 5 times as many blue marbles as red marbles.
After he buys an equal number of blue and red marbles,
the number of blue marbles is 4 times that of the red marbles.
- How many blue marbles are there in the end?
- How many red marbles are there in the end?
- How many marbles are there in the end?
- How many marbles does Adam buy?
|
Blue marbles |
Red marbles |
Difference |
Before |
5 x 3 = 15 u |
1 x 3 = 3 u |
4 x 3 = 12 u |
Change |
+ ? |
+ ? |
|
After |
4 x 4 = 16 u |
1 x 4 = 4 u |
3 x 4 = 12 u |
(a)
The difference in the number between the blue and red marbles at first and in the end remains unchanged.
LCM of 4 and 3 is 12.
15 u = 105
1 u = 105 ÷ 15 = 7
Number of blue marbles in the end
= 16 u
= 16 x 7
= 112
(b)
Number of red marbles in the end
= 4 u
= 4 x 7
= 28
(c)
Total number of marbles in the end
= 112 + 28
= 140
(d)
Total number of marbles that Adam buys
= (16 u - 15 u) x 2
= 1 u x 2
= 2 u
= 2 x 7
= 14
Answer(s): (a) 112; (b) 28; (c) 140; (d) 14