The correct representations of the system are:
- Budget constraint: \(40x + 60y \leq 2,000\)
- Water constraint: \(15x + 10y \leq 400\)
Options c and f accurately express these constraints.
Let's define the system of linear inequalities based on the given information:
1. Budget Constraint:
 The cost of maple trees (\$40 each) and birch trees (\$60 each) must not exceed the budget of \$2,000.
 \[ 40x + 60y \leq 2,000 \]
 So, option c is correct.
2. Water Constraint:
 The total water required by maple trees (15 gallons each) and birch trees (10 gallons each) must not exceed 400 gallons.
 \[ 15x + 10y \leq 400 \]
 So, option f is correct.
None of the other options accurately represents the system of linear inequalities.