Initial wage : $100
New wage = 25% more = 125

Reduced no of hours * new wage = initial wage (employee's total weekly salary would remain unchanged)

x*125 = 100
x = 100/125 = 4/5 = 0.8

The number of hours worked be reduced is 20% {(1-0.8)*100}

Let's use numbers.

Say the employee used to work for $4/hour - for 40 hours per week. So his daily take-home was $160/week.

So a 25% increase would mean he now gets paid $5/hour. How many hours does he need to work to still make $160/week?

160/5 = 32 hours/week.

So what's the % change? (32-40)/40 = a decrease of 20%.

Answer B.

thanks... had a made a very silly mistake...
Answer is B.