Tourist purchased a total of 30 travelers checks in $50 and $100 denominations. The total worth of the travelers checks is $1800. How many checks of $50 denominations can he spend so that average amount (arithmetic mean) of the remaining travelers checks is $75?
Choose the correct choice:  A) 4  B) 18  C) 15  D) 20  E) 24
you could set-up a quick table and brute force the answer.   A	4	*	50	200 1800	-200 1600	26 61.54   18	18	*	50	600 1800	-900 0900	12 75.00   C	15	*	50	750 1800	-750 1050	15 70.00   D	20	*	50	1000 1800	-1000	800	10 80.00   E	24	*	50	1200 1800	-1200	600	6 100.00   Answer is 18
<result>B</result>
Tourist purchased a total of 30 travelers checks in $50 and $100 denominations. The total worth of the travelers checks is $1800. How many checks of $50 denominations can he spend so that average amount (arithmetic mean) of the remaining travelers checks is $75?