Billy and Simon had an equal number of books. Billy donated
17 of her books and Simon donated
15 of his books. Simon donated 20 more books than Billy. How many books did Simon have at first?
| |
Billy |
Simon |
Before
|
7x5 =
35 u |
5x7 =
35 u |
Change
|
- 1x5 =
- 5 u |
- 1x7 =
- 7 u |
After
|
6x5 =
30 u |
4x7 =
28 u |
The number of books that Billy and Simon each had at first is the same. Make the number of books that Billy and Simon had at first the same. LCM of 7 and 5 is 35.
Number of books that Simon donated more than Billy
= 7 u - 5 u
= 2 u
2 u = 20
1 u = 20 ÷ 2 = 10
Number of books that Simon had
= 35 u
= 35 x 10
= 350
Answer(s): 350
