Question

A girl bought some pencils, erasers, and paper clips at the stationery store. The pencils cost IDR. 1000 each, the erasers cost
IDR. 500 each and the paper clips cost 2 for IDR. 100. If she bought total cost IDR. 10000, how many of each did she buy ?

I wrote :
Pencil = X = IDR. 1000
Eraser = Y = IDR. 500
Paper Clip = IDR. 100/2 = IDR.50

1000X + 500Y + 50Z = 10000
Then ? I'm confuse...
How to solve ?

Answer 1

divide your equation by 50

20x + 10y + z = 200

remember that x, y, and z must be positive whole numbers.
Are we allowed to have zero of any of them ????
I will let you decide that
z = 200 - 20x - 10y
maximum value of x has to be 9, (if x=10, z = 0)
maximum value of y has to be 19

So there are multiple answers.
You could set up a chart to show them

x y z
1 1 170
1 2 160
1 3 150
...
1 17 10
1 18 0 ---> but it said she bought "some", so I guess we should allow that
1 19 -10 ----- NO
2 1 150
...
9 1 10
9 2 0 --- ???
9 3 -10 ---NO