7.Hasan buys two kinds of cloth materials for school uniforms, shirt material that costs him ₹ 50 per metre and trousers material that costs him ₹ 90 per metre. For every 3 metres of the shirt material, he buys 2 metres of the trouser material. He sells the materials at 12% and 10% profit respectively. His total sale is ₹ 36,600. How much trouser material did he buy?

Given that for every 3 metres of the shirt material, he buys 2 metres so the ratio of shirt material brought to the trouser material bought = 3 : 2
Let the shirt material bought = 3x m

and trouser material bought = 2x m

Cost of shirt material = 50 × 3x = ₹ 150x

Cost of trouser material = 90 × 2x = ₹ 180x

Also, profit in case of shirt material=12%

∴ It's selling price=\(₹(150x×\frac{112}{100}\))=₹168x

Also, profit in case of trouser material=10%

∴ It's selling price=\(₹(180x×\frac{110}{100}\))=₹198x

∴ Total selling price=₹(168x+198x)=₹366x

But we have the total selling price as ₹36660

∴ 366x=36660

\(\Rightarrow\ x=\frac{36660}{366}=100.16\)

Thus, the trouser material purchased =2x=2×100.16m≈200 meters.