The answer to that question is x=20
He used 7 pints all together because there at 2 cups in each pint and 4 pints in a half a gallon.

if you have already covered slopes, you could also get it that way, in fact is simpler that way.
Answer: 3
Explanation: logarithm base 8 of 512 is 3
1 + 5 = 6
3 + 3 = 6
3 + 47 = 50
7 + 43 = 50
13 + 37 = 50
19 + 31 = 50