From an $$850,000$ retirement fund Arthur will receive equal payments at the beginning of every month for $30$ years. Using an interest rate of $5\mathrm{.}4\%$ compounded monthly, calculate the size of the monthly payments. a$$4,751\mathrm{.}63$ b$$4,385\mathrm{.}02$ c$$6,018\mathrm{.}77$ d$$2,592\mathrm{.}55$