### Theory:

In the previous lesson we learn to perform the addition using the grid models. Now let us take a look how to perform a subtraction using a grid models.
Example:
Find $$0.55 – 0.15$$.

Here, $$0.65$$ can be written as $\frac{55}{100}$, and $$0.15$$ can be written as $\frac{15}{100}$.
• In the grid model first shade the region of $$0.55$$ and cross out the regions $$0.15$$, which means we are excluding $$0.15$$ from the total shaded area.
• The left out shaded regions without the cross marks are the difference between $$0.55$$ and $$0.15$$.
• Therefore, the difference is $$0.55 – 0.15 = 0.40$$

Now let's see word problems to understand this concept clearly.
Example:
Riya's mother gave her $$₹ 5.50$$ and she used this money to buy a pen. If the shopkeeper gave her $$₹ 1$$ what was the pen's rate?

To find the pen's rate, subtract the total amount $$₹ 5.50$$ with the returned amount $$₹ 1$$.

That is, $$₹(5.50 – 1) = ₹ 4.50$$. Therefore the cost of the pen is $$₹ 4.50$$.
In the upcoming exercises we practice to solve more problems in this concept.