I have 9 coins, and they equal .60cent. I need two combinations.... myou're first combination is:
1 quarter
3 dimes
5 pennies
What's the 2nd combo?
If you have to use all 9 coins, the solution you gave is the only one to produce 60 cents, and use all 9 coins
If you can use any number of your 9 coins, then
2 quarters
1 dime
0 pennies would be an option
To prove that there is only 1 way using all 9 coins, consider this little computer program:
10 FOR X=1 TO 9
20 FOR Y = 1 TO 9
30 FOR Z = 1 TO 9
40 IF X+Y+Z=9 THEN 50 ELSE 70
50 SUM = 25*X+10*Y+Z
60 IF SUM = 60 THEN PRINT X,Y,Z
70 NEXT Z
80 NEXT Y
90 NEXT X
Ok
run
1 3 5
Ok