Take a look at the sentence again:
A crumpled ten-dollar bill __________ at the bottom of the washing machine.
Mike retrieved the money and drove to Tito's Taco Palace, where he bought
fifteen tacos and a large root beer.
The ten-dollar bill rested at the bottom of the washing machine. Thus, you need a form of lie. Since the sentence is past tense, you need the simple past form. Consult the table below or review the rules.
| Infinitive | Definition | Simple Present | Simple Past | Past Participle | Present Participle |
| to lay | to put something down | lay(s) | laid | laid | laying |
| to lie | to rest or recline | lie(s) | lay | lain | lying |