Ratio and Proportion Practice Test 1

Let the number of seats for Mathematics, Physics and Chemistry be 5x, 7x and 8x originally.
Now,
Number of seats for Mathematics $=\frac{140}{100}\times 5\mathit{x}=7\mathit{x}$
Number of seats for Physics $=\frac{150}{100}\times 7\mathit{x}=\frac{21}{2}\mathit{x}$
Number of seats for Chemistry $=\frac{175}{100}\times 8\mathit{x}=14\mathit{x}$
Hence, ratio of increased seats $=7\mathit{x}:\frac{21}{2}\mathit{x}:14\mathit{x}=2:3:4$