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.