To represent the cost to have floors carpeted, we start by identifying the components of the cost based on the given information:
- The cost per room is $100. Therefore, if \( r \) is the number of rooms, the cost for carpeting \( r \) rooms is \( 100r \).
- There is a flat installation fee of $50.
To find the total cost \( c \), we combine these two components:
\[ c = 100r + 50 \]
This equation is in slope-intercept form \( y = mx + b \), where:
- \( m \) (the slope) is the cost per room, which is 100,
- \( b \) (the y-intercept) is the fixed installation cost, which is 50.
Therefore, the final linear equation to represent the cost to have floors carpeted is:
\[ c = 100r + 50 \]