Calculated the dollar rates of return on the following assets:

a$.$ A painting whose price rises from $$200,000$ to $$250,000$ in a year

b$.$ A $10,000$ deposit in a London bank in a year when the interest rate on pounds is $10\%$ and the $$/$ exchange rate moves from $$1\mathrm{.}5$ per pound to $$1\mathrm{.}38$ per pound.