Question

Write an algebraic expression for:
One-fifth of a number added to thrice the number subtracted from the even prime number.

Answer 1

Hint: In the given question, we are required to write an algebraic expression based on the information given to us. First, break down the information given to us to try and identify what algebraic expression must look like. You should always know what you are dealing with. A sum means that you are adding something, so you are going to use the $ + $ sign.

Complete step-by-step answer:
“One-fifth of a number added to thrice the number subtracted from the even prime number” means first calculating one-fifth of a number and then adding it to thrice the number. Then, subtracting the sum of the two entities from the even prime number.
So, we first have to compute the sum of the two entities.
Let the unknown number be x.
Then, the sum of one fifth of the number and thrice of the same number can be denoted as $ \dfrac{x}{5} + 3x $
So, the algebraic expression for the above statement is $ \left( {\dfrac{x}{5} + 3x} \right) $ .
The only even prime number is two. So, we have to subtract the sum obtained from $ 2 $ .
Hence, we get, $ 2 - \left( {\dfrac{x}{5} + 3x} \right) $
Simplifying the expression, we get,
 $ \Rightarrow 2 - \left( {\dfrac{{16x}}{5}} \right) $
Opening the bracket, we get,
 $ \Rightarrow 2 - \dfrac{{16x}}{5} $

Note: When we combine numbers and variables in a valid way, using operations such as addition, subtraction, multiplication, division, exponentiation, and other operations and functions as yet unlearned, the resulting combinations of mathematical symbols is called a mathematical expression. An expression is a sentence with a minimum of two numbers and at least one math operation. This math operation can be addition, subtraction, multiplication, and division.