The margin requirement on the S&P $500$ futures contract is $16\%,$ and the stock index is currently $1,500.$ Each contract has a multiplier of $$50.$a$.$ How much margin must be put up for each contract sold? b$.$ If the futures price falls by $1\%$ to $1,485,$ what will happen to the margin account of an investor who holds one contract? $($Input the amount as a positive value.$)$ c$-1.$ What will be the investor's percentage return based on the amount put up as margin? $($Negative value should be indicated by a minus sign. Round your answer to $2$ decimal places.$)$ c$-2.$ What would be the current cash balance in the margin account?