Writing Mathematical Expression

In mathematics, we can divide expression in two ways. That is -

1) Numerical Expression
2) Algebraic Expression

Here, by the word 'expression' or 'mathematical expression' we would like to define it as mathematical phrase that contains number,operator,variable or symbol etc.

Numerical Expression
A numerical expression contains numbers and operations. For example:

5+ 3
35÷7
53·4
94 - 31
102 - 9·3

All are example of numerical expression because it contains only number and operator.
Word problem: Robin plays football for 1.5 hours in the morning and 1 hour in the afternoon. He does this for a total of 30 days. Write a numerical expression with parentheses for the total number of hours Robin played football.

30 · (1.5 + 1)

Algebraic Expression
An algebraic expression contains numbers,operations and variables . For example:

5x + 3
9y - 8
6 + 3d
x/9

Word problem: Marco's mom gave him 'd' dollars for his allowance for a week. He also earned $14.55 for his newspaper route that week. How much money does Marco have? Write your answer as an expression.

d+14.55