What is the algebraic expression for five times the sum of seven and a number?

Hint: Let us consider the unknown number as $x$. We use the symbol $+$ for addition. The sum of two numbers is given by $a+b$. When we multiply a number with another number, we use the symbol $\cdot $. We know that an algebraic expression is the combination of variables, constants and algebraic symbols. Based on the conditions given we can frame an algebraic expression.

Complete step by step solution:
We have been asked to find the algebraic expression for five times the sum of seven and a number.
Let us consider the unknown number to be $x$.
We know that the sum of the unknown number with seven is given by using the symbol $+$.
Thus, it can be written as:
$7+x$ …(1)
We have the term five times, which means that something is being multiplied five times.
So, it is given that the sum of seven and the number is multiplied by 5. Then from equation (1) we get,
$5\left( 7+x \right)$
This is the required algebraic expression for the given condition.

Note: It should be kept in mind that the algebraic sum is formed after proper analysis of statement as it may sometimes be confusing that whether the sum of 5 and 7 is to be taken or 7 and unknown number in this case the answer obtained will be:
$\left( 5+7 \right)x$
Hence the answer obtained is not the same and it is a common mistake that can occur.