Let the fixed cost be x and the variable cost per hour be y.
Then,
x+10y=600 …(1)
x+15y=840 …(2)
Subtracting equation (1) from equation (2), we have,
5y=240
⇒y=48
Putting y=48 in equation (1), we get x+10×48=600
⇒x=600−480
⇒x=120
∴ The fixed cost is ₹120 and the variable cost is ₹48/hr.