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 $100?  Choose the correct choice from the following choices.
A) 4 B) 12 C) 15 D) 22 E) 24
you could set-up a quick table and brute force the answer.   A	4	*	50	200 1800	-200 1600	26 61.54   B	12	*	50	600 1800	-600 1200	18 66.67   C	15	*	50	750 1800	-750 1050	15 70.00   22	22	*	50	1000 1800	-1000	800	8 100.00   E	24	*	50	1200 1800	-1200	600	6 100.00   Answer is 22
<result>D</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 $100?