Kathy has a bag containing some black and purple stickers. If she adds in 14 black stickers, 25% of the stickers in the bag are purple. If she adds in another 14 purple stickers, 50% of the stickers in the bag are purple. How many black stickers are in the bag?
| |
Black stickers |
Purple stickers |
| Before |
3 u - 14 |
1 u |
| Change 1 |
+ 14 |
|
| After 1 |
3x1 =
3 u |
1x1 =
1 u |
| Change 2 |
|
+ 14 |
| After 2 |
1x3 =
3 u |
1x3 =
3 u |
25% =
25100 =
1450% =
50100 =
12The number of black stickers remains unchanged at the second change when she adds in another 14 purple stickers. Make the number of black stickers the same at the second change. LCM of 3 and 1 is 3.
Number of purple stickers added
= 3 u - 1 u
= 2 u
2 u = 14
1 u = 14 ÷ 2 = 7
Number of black stickers at first
= 3 u - 14
= 3 x 7 - 14
= 21 - 14
= 7
Answer(s): 7
