To determine how many windows must a house have for Company A's total cost to be less expensive than Company B's total cost, we can set up inequalities based on the given information.
For Company A:
- Fixed cost for power-washing the siding: $312
- Additional cost for each window: $12 per window
So, the total cost for Company A can be represented as:
\[
C_A = 312 + 12w
\]
where \( w \) is the number of windows.
For Company B:
- Cost per window (which includes siding): $36
So, the total cost for Company B can be represented as:
\[
C_B = 36w
\]
We want to find the inequality where Company A's cost is less than Company B's cost:
\[
312 + 12w < 36w
\]
Now, we can simplify this inequality:
- Subtract \( 12w \) from both sides:
\[
312 < 36w - 12w
\]
- Combine like terms:
\[
312 < 24w
\]
- Divide both sides by 24:
\[
\frac{312}{24} < w
\]
- Simplify:
\[
13 < w
\]
This can be written as:
\[
w > 13
\]
Thus, a house must have more than 13 windows for Company A to be less expensive than Company B.