In a stationery shop, the number of rulers was
310 of the total number of rulers and pencils together. Cody sold the rulers and pencils in sets of 1 ruler and 10 pencils. After selling all the pencils, he still had 161 rulers left. How many pencils were in the stationery shop at first?
| |
Rulers |
Pencils |
| Before |
3x10 =
30 u |
7x10 =
70 u |
| Change |
- 1x7 =
- 7 u |
- 10x7 =
- 70 u |
| After |
161 |
0 |
Since all the pencils were sold, the number of pencils at first and the number of pencils sold were the same. Make the number of pencils at first and sold the same. LCM of 7 and 10 is 70.
Number of rulers sold
= 30 u - 7 u
= 23 u
23 u = 161
1 u = 161 ÷ 23 = 7
Number of pencils at first
= 70 u
= 70 x 7
= 490
Answer(s): 490
