Suppose that the number of thousands ofinsects killed by two brands of pesticide is given by:

f(x,y)= 10,000-6500^-0.01x-3500e^-0.02y

where x is the number of liters of brand 1 and y is the number of liters of brand 2. What is the rate of change of insect deaths with respect to the number of liters of brand 1 if 100 liters of each brand are currently being used?

Please explain work.

Thanks,