To determine the total cost for a monthly usage of 1,200 gallons using the given function \( c = 0.25x + 20 \), we substitute \( x = 1200 \) into the equation:
\[ c = 0.25(1200) + 20 \]
Calculating \( 0.25 \times 1200 \):
\[ 0.25 \times 1200 = 300 \]
Now add the fixed fee:
\[ c = 300 + 20 = 320 \]
Thus, the total cost for using 1,200 gallons of water is $320. The point that accurately represents this monthly usage is \( (1,200, 320) \).
From the options you provided:
- \( (320, 1,200) \)
- \( (1,200, 320) \)
- \( (1,200, -180) \)
- \( (1,200, 300) \)
The correct answer is (1,200, 320).