Billy and Daniel had an equal number of books. Billy donated
19 of her books and Daniel donated
17 of his books. Daniel donated 20 more books than Billy. How many books did Daniel have at first?
| |
Billy |
Daniel |
Before
|
9x7 =
63 u |
7x9 =
63 u |
Change
|
- 1x7 =
- 7 u |
- 1x9 =
- 9 u |
After
|
8x7 =
56 u |
6x9 =
54 u |
The number of books that Billy and Daniel each had at first is the same. Make the number of books that Billy and Daniel had at first the same. LCM of 9 and 7 is 63.
Number of books that Daniel donated more than Billy
= 9 u - 7 u
= 2 u
2 u = 20
1 u = 20 ÷ 2 = 10
Number of books that Daniel had
= 63 u
= 63 x 10
= 630
Answer(s): 630
