28]
SECTION V—QUANTITY PROBLEMS
69
Multiply 3 by 4.
| 1 | 3 | |
| 2 | 6 | |
| \ | 4 | 12; |
| The quantity is | 12 | |
| 1⁄4 | 3 | |
| Total | 15. | |
Problem 27
A quantity and its 1⁄5, added together become 21. What is the quantity?
Assume 5.
| \ | 1 | 5 |
| \ | 1⁄5 | 1 |
| Total|6. | ||
As many times as 6 must be multiplied to give 21, so many times 5 must be multiplied to give the required number.
| \ | 1 | 6 |
| \ | 2 | 12 |
| \ | 1⁄2 | 3 |
| Total | 31⁄2 | |
| \ | 1 | 31⁄2 |
| 2 | 7 | |
| \ | 4 | 14. |
| The quantity is | 171⁄2 | |
| 1⁄5 | 31⁄2 | |
| Total | 21. | |
Problem 28
A quantity and its 35 are added together and from the sum 1⁄3 of the sum is subtracted, and 10 remains. What is the quantity?
Subtract from 10 its 1⁄10, which is 1. The remainder is 9. This is the quantity; its 2⁄3, 6, added to 9, makes 15, and 1⁄3 of 15, taken away from 15, leaves 10. Do it thus . . . .
