It depends on if tanks means gallons. If so, then the answer is 3 1/5 because there are 8 pints in 1 gallon. Add 4 and 4 together to get 8. That's 1 full tank. Then add 4 and 4 again to get 16. That's 2 full tanks. Now, add 4 and 4 again to get 24. Since you can't add 4 and 4 (8), to 24 without going over 30, then you make a fraction or a remainder. The fraction/remainder is 6 left out of 30, or 6/30. Simplify that and you get 1/5. Your answer is then 3 1/5.