Originally, let the number of seats for Mathematics, Physics and Biology be 5x, 7x and 8x respectively.
After increase, the number of seats are (140% of 5x), (150% of 7x) and (175% of 8x).
→ 140100 × 5x, 150100 × 7x, 175100 × 8x
→ 7x, 21x2, 14x
∴ The required ratio = 7x:21x2:14x
→14x : 21x : 28x
→ 2 : 3 : 4