Adam has 50 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 2 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 1 = 5 u |
1 x 1 = 1 u |
4 x 1 = 4 u |
Change |
+ ? |
+ ? |
|
After |
2 x 4 = 8 u |
1 x 4 = 4 u |
1 x 4 = 4 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 1 is 4.
5 u = 50
1 u = 50 ÷ 5 = 10
Number of blue marbles in the end
= 8 u
= 8 x 10
= 80
(b)
Number of red marbles in the end
= 4 u
= 4 x 10
= 40
(c)
Total number of marbles in the end
= 80 + 40
= 120
(d)
Total number of marbles that Adam buys
= (8 u - 5 u) x 2
= 3 u x 2
= 6 u
= 6 x 10
= 60
Answer(s): (a) 80; (b) 40; (c) 120; (d) 60