A loan buyer in a secondary market believes that x% of the loans are high quality, and the rest are low quality. The buyer values high quality loans at $90,000 and low quality at $70,000. Banks selling loans value high quality loans at $85,000 and low quality at $55,000. If the buyer cannot observe the bond's type, then the minimum x that will support trade in both types is?

40%

50%

60%

75%