Kathy bought four times as many biscuits as Sam. After Kathy ate 3 biscuits, she had 12 more biscuits than Sam. How many biscuits did they buy altogether?
| |
Kathy |
Sam |
Total |
| Before |
4 u |
1 u |
5 u |
| Change |
- 3 |
|
|
| After |
4 u - 3 |
1 u |
|
The number of biscuits that Sam had remains unchanged.
If Sam had another 12 biscuits in the end, the number of biscuits that Kathy and Sam had would be the same.
4 u - 3 = 1 u + 12
4 u - 1 u = 12 + 3
3 u = 15
1 u = 15 ÷ 3 = 5
Total number of biscuits
= 4 u + 1 u
= 5 u
= 5 x 5
= 25
Answer(s): 25
