The price of fuel decreases by 45%, 60% and 55% in three successive months, but increases by 50% in the fourth month.

Assume the original price of fuel = 100.

After 1st month (45% decrease)

New price = $100 \times 0.55 = 55$

After 2nd month (60% decrease)

New price = $55 \times 0.40 = 22$

After 3rd month (55% decrease)

New price = $22 \times 0.45 = 9.9$

After 4th month (50% increase)

New price = $9.9 \times 1.5 = 14.85$

Compare with original price

Original price = 100
Final price = 14.85

Decrease = $100 - 14.85 = 85.15$

Percentage decrease = $85.15%$

✅ Final Answer: 85.15% decrease