Question

One fifth of a number 9. Find the number.

Answer 1

Hint: irst we need to convert the given word problem into algebraic expression. That is an algebraic expression in mathematics is an expression which is made up of variables and constants along with algebraic operations. An expression is a group of terms. Here algebraic operations are addition, subtraction, division and multiplication etc. After obtaining the algebraic expression we can simplify.

Complete step by step answer:
Now they have given One fifth of a number 9.
We know that one fifth means
\[ \Rightarrow \dfrac{1}{5}\]
Now one fifth of a number. We don’t know that number so we take that unknown number as a variable ‘x’.
Then we have given One fifth of a number means
\[ \Rightarrow \dfrac{1}{5}a\]
Finally One fifth of a number is 9.
\[ \Rightarrow \dfrac{1}{5}a = 9\]
Now we can simplify this.
Now multiply 5 on both sides of the equation
\[ \Rightarrow a = 9 \times 5\]
\[ \Rightarrow a = 45\]
Hence the required number is 45.

Note: Algebra helps in converting a mathematical statement into an equation. We know if we have ‘more’ or ‘sum’ in the given sentence we use addition operation\[( + )\]. Similarly If we have ‘less’ or ‘difference’ we use subtraction \[( - )\]. If we have ‘quotients’ we use division operation \[( \div )\]. To define more generalized terms; we use algebra. It is a very vast branch of mathematics and is used in all the branches of mathematics like polynomial, linear equations, graphs, etc. and in daily life too.