How would I write the equation y=3.9657(0.9982^x) in the format of g(x)=f(x)+f(x-60)?

.9982^-60 = 1.1142, so

.9982^(x-60) = 1.1142*.9982^x

So, just split 3.9657 into two parts, such as 1+2.9657:

g(x) = f(x) + 2.9657/1.1142 f(x-60)