Answer:
Fish B = 2 Inch
Fish A = 4 Inch
Explanation:
First lets get some information
Hank has 20 Gallons Water, 3 Fish A, 4 Fish B
Marta has 16 Gallons Water, 3 Fish A, 2 Fish B
Next we need to fins the easiest way to solve this and that would be looking at fish B the difference is that Hank has 2 more B fish than Marta and a 4 Gallon difference that says Each B fish is a length of 2 inches ( 1 inch per gallon).
Fish B = 2 Inch
Now that we have Fish B solved we can solve fish A. Using what we know we can Find the amount of water used by the B fish and take the rest of the water and Divide it by the number of Fish A.
Hanks Water From Fish B = 4x2, so in this Case 8gallons
Marta's Water From fish B = 2x2, so in this Case 4 Gallons
This Leaves 12 Gallons for Hank and 12 gallons for Marta's.
Next we need to Divide 12 by the number of A fish used, in this case 3
12 / 3= 4
Fish A = 4 Inch
If you wanted to double check your work you Could Multiply Both Fish A and B by the number of that fish in their equarium and add them together to get your total gallons of water.