Neave, Sam and Justin had 144 pencils. After Neave used 23 pencils and Sam used
13 of her pencils, Neave had thrice as many pencils left as Sam. Justin bought another 32 pencils, he had four times the number of pencils Sam had left. How many pencils did Justin have at first?
| |
Neave |
Sam |
Justin |
Total |
| Before |
6 u + 23 |
3 u |
8 u - 32 |
144 |
| Change |
- 23 |
- 1 u |
+ 32 |
|
| After |
6 u |
2 u |
8 u |
|
Comparing Neave
and Sam in the end |
3 |
1 |
|
|
Comparing Justin
and Sam in the end |
|
1 |
4 |
|
Number of pencils that Neave had in the end
= 3 x 2 u
= 6 u
Number of pencils that Justin had in the end
= 4 x 2 u
= 8 u
Total number of pencils at first
= 6 u + 23 + 3 u + 8 u - 32
= 17 u - 9
17 u - 9 = 144
17 u = 144 + 9
17 u = 153
1 u = 153 ÷ 17 = 9
Number of pencils that Justin had at first
= 8 u - 32
= 8 x 9 - 32
= 72 - 32
= 40
Answer(s): 40
