A spieces of extremely rare, deep water fish are slowly becoming extinct. If there are a total of 821 of this type of fish and there are 15% fewer fish each month, how many wil there be in half a year

12 months in a year

6 is half a month so we're going off of 6 months.

So:

821*0.15 = 123.15

821 - 123.15 = 697.85

697.85*0.15 = 104.6775

697.85-104.6775 = 593.1725

593.1725*0.15 = 88.975875

593.1725-88.975875 = 504.196625

504.196625 * 0.15 = 75.62949375

504.196625 - 75.62949375 = 428.56713125

428.56713125*0.15 = 64.2850696875

428.56713125-64.2850696875 = 364.282061562

364.282061562*0.15 = 54.6423092344

364.282061562-54.6423092344 = 309.639752328

So its 310 fish.