a is the initial value of the computer so a=1500

b is the common ratio so

b=0.8

The exponential function is: \(\displaystyle{f{{\left({x}\right)}}}={1500}\cdot{\left({0.8}\right)}^{{x}}\)

b is the common ratio so

b=0.8

The exponential function is: \(\displaystyle{f{{\left({x}\right)}}}={1500}\cdot{\left({0.8}\right)}^{{x}}\)