The variable x represents the number of angelfish carlos bought and the variable y represents the number of parrotfish he bought.
carlos bought 405 tropical fish for a museum display. he bought 8 times as many parrotfish as angelfish.
how many of each type of fish did he buy

If you would like to know how many of each type of fish did Carlos buy, you can calculate this using the following steps:

x ... the number of angelfish
y ... the number of parrotfish
405 tropical fish bought
8 times as many parrotfish as angelfish ... 8 * y = x

405 = x + y
405 = 8 * y + y
405 = 9 * y
y = 405 / 9
y = 45 parrotfish

x = 8 * y = 8 * 45 = 360 angelfish

The correct result would be 45 parrotfish and 360 angelfish.