Answer:
Number of catfish = 28
Step-by-step explanation:
Let the number of catfish = c
Number of angle fish = c + 6
Number of guppies = 4*(c + 6) = 4c + 4*6 = 4c + 24
Total fishes = 198
c + c + 6 + 4c + 24 = 198 {Combine like terms}
c + c +4c + 6 + 24 = 198
6c + 30 = 198 {Subtract 30 from both sides}
6c = 198 - 30
6c = 168
c = 168/6 {Divide both sides by 6}
c = 28
your calculations for volume (pi x r^2 × h) and surface area (2 × pi × r (h+r)) are correct. However your ratio are incorrect. From the formulas the ratio of surface area to volume would be r×h:2(h+r)
5ax+2a=9a
5ax+2a-2a=9a-2a
5ax =7a
5ax/5a =7a/5a
x=7/5
10/100 = x / (810+x)
1/10 = x / (810 + x)
10x = 810 + x
9x = 810
x = 90 g salt
mass of solution = mass of water + mass of salt
ms = mw + m salt
ms = 810 + 90
ms = 900 g of solution
