### Theory:

An expression can also be written in the form of a situation.
Let us consider the following situation.

Meera has $$9$$ chocolates more than Vinod.

Let the number of chocolates with Vinod be '$$x$$'.

We know that Meera has $$9$$ more chocolates than what Vinod has.

Then, the number of chocolates with Meera $$=$$ the number of chocolates with Vinod $$+$$ $$9$$

$$=$$ $$x$$ $$+$$ $$9$$

Therefore, Meera has $$x$$ $$+$$ $$9$$ chocolates.

In this example, 'the number of chocolates with Vinod' is the variable and 'the number of chocolates with Meera' is the expression.

Let us also look at a few more examples.

 Situation Variable Expression Deepak is twice as old as Tanvi. Let the age of Tanvi be '$$x$$'. Multiply Tanvi's age by $$2$$ to get Deepak's age. Therefore, Deepak's age is $$2x$$. The tiger is $$6$$ cages behind the bear. Let the bear's cage be '$$y$$'. Subtract $$6$$ cages from the bear's to get to the tiger's cage. Therefore, the tiger's cage is $$y - 6$$. The building $$4$$ feet taller than the tree. Let the height of the tree be '$$z$$'. Add $$4$$ feet to $$z$$ to get the height of the building. Therefore, the height of the building is $$z + 4$$. Lata ate half of the chocolates from the bag. Let the number of chocolates in the bag be '$$q$$'. Divide $$q$$ by $$2$$ to get the number of chocolates Lata ate. Therefore, Lata has eaten $$\frac{q}{2}$$ chocolates.