To find the cost of the typewriter to ABC, we can use the relationship between the cost, the selling price, and the markup.
Let \( C \) be the cost of the typewriter. ABC Office Supply sells the typewriter for $129.95, and they have a 15% markup on cost. This means the selling price is equal to the cost plus 15% of the cost. We can express this mathematically as:
\[ \text{Selling Price} = C + 0.15C \]
This simplifies to:
\[ \text{Selling Price} = 1.15C \]
Now, we can set this equal to the selling price of $129.95:
\[ 1.15C = 129.95 \]
To find \( C \), divide both sides by 1.15:
\[ C = \frac{129.95}{1.15} \]
Calculating that gives:
\[ C \approx 113.00 \]
Thus, the cost of the typewriter to ABC was approximately $113.00.