Answer:
We can have 7 fish in fish tank containing 35 gallons of water.
Step-by-step explanation:
Given:
2 fish per 10 gallons
∴ 1 fish can be in = 
To find Number of fish in 35 gallons of water
Number of fish in 35 gallons would be = 
3 squares = 4 circles, so (number of squares)/(number of circles) = 3/4.
3/4 = 12/16
:::::
4 squares = 2 circles, so (number of squares)/(number of circles) = 4/2.
4/2 = 2/1
:::::
2 squares = 5 circles, so (number of squares)/(number of circles) = 2/5.
2/5 = 4/10
Answering from phone so this will be a bit messy.
a
b=a+1
c=b+1=a+2
2a=b+20
Therefore:
2a=a+1+20
a=21,b=22,c=23
I don't know use a calculator