1.williamson, 5th edition, problem 2.12 (slightly modified).you need to do this problem in excel. letktdenote the quantity of capital a country has at the beginning of periodt. also, suppose that capitaldepreciates at a constant rateδ, so thatδktof the capital stock wears out during periodt. if investmentduring periodtis denoted byit, and the country does not trade with the rest of the world, then we can saythat the quantity of capital at the beginning of periodt+1 is given bykt+1=(1−δ)kt+it. this equation is often referred to as the "law of motion for capital." suppose at the beginning of year 0 thatthis country has 80 units of capital. investment expenditures are 10 units in each of years 0,1,2,3,.the capital stock depreciates by 10% per year.(a) calculate the quantity of capital at the beginning of years 0,1,2,3,.(b) repeat 1a, except assume now the country begins year 0 with 100 units of capital. explain whathappens now, and discuss your results.