Let's define some notation first:
H= number of Hogwarts, R= number of robes, Q= number of Quidditch
We can set up the following equation for the total of clothing items:
![H+R+Q=200](https://img.qammunity.org/2023/formulas/mathematics/college/m281c2kvmfn5eei9i2vbvdxfxgn3b5rn4n.png)
We also know that Q= 2R so we have:
![H+3R=200](https://img.qammunity.org/2023/formulas/mathematics/college/y6rdt5lv0yc7fsle6whs4z8j7x3hq49cex.png)
Now we can create an equation for the amount of money and we have:
![12H+24R+36Q=6000](https://img.qammunity.org/2023/formulas/mathematics/college/6sxi8zjh48vfrfbffj3qcy7jt1467y8fth.png)
![12H+96R=6000](https://img.qammunity.org/2023/formulas/mathematics/college/u4jnp91py1hzfopukekdwyjlg4avdpv3ip.png)
Now we can replace H=200-3R and we got:
![12(200-3R)+96R=6000](https://img.qammunity.org/2023/formulas/mathematics/college/kvo83v0rkjtjb88dzoenp5ujc51uqinv1s.png)
And solving for R we got:
![60R=3600](https://img.qammunity.org/2023/formulas/mathematics/college/2yspr599xsdlivhtfpe0radggyq86zgp9h.png)
![R=(3600)/(60)=60](https://img.qammunity.org/2023/formulas/mathematics/college/95ztwsic4c1vvwfn9o6gr6a8dxq4c29d7w.png)
And then Q would be:
![Q=2R=120](https://img.qammunity.org/2023/formulas/mathematics/college/stenf3q595p7hjhteea89n9u36vdrpttme.png)