Risa spent
23 of her money on 11 pens and 7 pencils. The cost of each pencil is 3 times the cost of each pen. She bought some more pens with
78 of her remaining money. How many pens did Risa buy altogether?
| 11 pens + 7 pencils |
Remaining
amount |
Total
amount |
| 2 p = 32 u |
1 p = 16 u |
3 p |
11
pens |
7
pencils |
More pens |
Left |
|
| |
|
7 |
1 |
|
| 11 u |
21 u |
14 u |
|
|
Cost of 1 pen = 1 u
Cost of 1 pencil = 3 u
Cost of 11 pens = 11 x 1 u = 11 u
Cost of 7 pencils = 7 x 3 u = 21 u
Cost of 11 pens + 7 pencils
= 11 u + 21 u
= 32 u
2 p = 32 u
1 p = 32 u ÷ 2 = 16 u
Amount of remaining money that Risa spent on buying more pens
=
78 x 16 u
= 14 u
Number of pens that Risa bought with
78 of her remaining money
= 14 u ÷ 1 u
= 14
Total number of pens that Risa bought
= 11 + 14
= 25
Answer(s): 25
