Final answer:
There are 10 lines on the ruler.
Step-by-step explanation:
The lines on the ruler are drawn at 10 cm intervals, which means that there is a line every 10 cm. We can calculate the number of lines by dividing the total length of the ruler by the interval between the lines. In this case, the total length of the ruler is 100 cm and the interval between the lines is 10 cm. So, the number of lines on the ruler is 100 cm / 10 cm = 10 lines.