Sam has 346 marbles and David has 471 marbles. How many marbles must David give to Sam so that Sam will have 79 less marbles than David?
|
Sam |
David |
Total |
Before |
346 |
471 |
817 |
Change |
+ ? |
- ? |
|
After |
1 u |
1 u + 79 |
817 |
The total number of marbles remains unchanged after David gives to Sam.
Total number of marbles
= 346 + 471
= 817
Total number of marbles in the end
= 1 u + 1 u + 79
= 2 u + 79
2 u + 79 = 817
2 u = 817 - 79
2 u = 738
1 u = 738 ÷ 2 = 369
Number of marbles that David must give to Sam
= 369 - 346
= 23
Answer(s): 23