Hard Math Question Help Mee

I Need To Make $2 Of Stamps using Only 3Cent Stamps And 8Cent Stamps In 12 Diffrent Ways!????

25: 8 cent stamps
22: 8 cent stamps and 8:3 cent stamps
19 : 8 cents stamps and 16 :3 cent stamps
16: 8 cents stamps and 24:3 cent stamps
13: 8 cents stamps and 32:3 cent stamps
10: 8 cents stamps and 40 :3 cent stamps
7 : 8 cents stamps and 48 :3 cent stamps
4: 8 cents stamps and 56 :3 cent stamps
1: 8 cents stamps and 64 :3 cent stamps

Can only come up with 9

Let us say the number of stamps of 3 cents that we use is X
Let us say the number of stamps of 8 cents that we use is Y

therefore, the equation that we want to satisfy is 3*X + 8*Y = 200 cents
or 8Y = 200 - 3X
or Y = 25 - (3X)/8


Now stamps cannot be in fractions or negative numbers
So ... Y must be greater than 0
and (3X/8) must be a whole number always i.e. X must be a multiple of 8.

So here are some solutions
X = 0, Y = 25
X = 8, Y = 22
X = 16, Y = 19
X = 24, Y = 16
X = 32, Y = 13
and so on.