100%-9%=91%
$819/91%=$900
100%+5%=105%
$900x105%=$945
Answer: He should sell it at $945 to make a profit of 5%.
The natural water sample contains only one type of bacteria.
the respiration rate will increase as temperature increases. An increase in temperature will minimize the amount of dissolved oxygen in the water and increase the metabolic rate of the goldfish, thus causing the goldfish's respiration rate to increase (“Hot waters make it hard for fish to breathe”).