单选题 Erica has $460 in 5-and 10-dollar bills only. If she has fewer 10-than 5-dollar bills, what is the least possible number of 5-dollar bills she could have?

【正确答案】 A
【答案解析】[解析] 设Erica有a张5美元的钞票，b张10美元的钞票，且a＞b，则根据题意可得：
5a+10b=46→a+2b=92→a=92-2b
由上式可知，a一定为偶数，所以(C)和(D)一定不对；因为a＞b，所以3a＞a+2b=92，再根据a为整数可知a一定大于30，所以(A)中的32是正确答案。