Tammy had some card collection.
37 of them were white and the rest were blue. She gave away 156 of the blue cards and 20% of the white cards. She then had
23 of her card collection left. How many cards did Tammy give away?
| |
White |
Blue |
Total |
Total |
Before
|
3x3 =
9 u |
4x3 =
12 u |
7x3 =
21 u |
3x7 =
21 u |
Change
|
- 0.6x3 =
- 1.8 u |
- 156 |
|
- 1x7 =
- 7 u |
After
|
2.4x3 =
7.2 u |
12 u - 156 |
|
2x7 =
14 u |
The total number of cards that Tammy had at first is repeated. Make the total number of cards at first the same. LCM 7 and 3 is 21.
Number of white cards that Tammy gave away
= 20% x 3 u
=
20100 x 3 u
= 0.6 u
1.8 u - 156 = 7 u
7 u - 1.8 u = 156
5.2 u = 156
1 u = 156 ÷ 5.2 = 30
Number of cards that Tammy gave away
= 7 u
= 7 x 30
= 210
Answer(s): 210
