what are all of the positive integer solutions of 7x - 5y = 3 such that x + y belongs to [20, 30] (inclusive) ?
I find one
[ x, y] = [ 9, 12 ]
Hi Chris
Once you have one you can find all
7(9)-5(12)=3
7(9+5k)-5(12+7k)=3
See I have added 35k and then taken it away again.
Obviously the question only wants the pairs that add to between 20 an 30
So
20<=21+12k<=30
-1<=12k<=9
-1/12 <=k <= 9/12
-1
K= 0
There is only the one answer.
OK..thanks, Melody.....I see that !!!
+160 
