Question

$20$ multiplied by a number, decreased by $15$ equal \[25\]. How do you find the number?

Answer 1

Hint: For finding out the required number, we can let it equal to some arbitrary variable, say x. In the above question, we have been given a mathematical statement which states that multiplying $20$ with x and decreasing it by $15$ gives us \[25\]. We can write the given statement as a mathematical statement so as to form a mathematical equation in terms of the variable x which can be solved for the variable x for finally finding out the required number.

Complete step-by-step answer:
Let the required number be x.
According to the above question, it is given to us that after multiplying $20$ with the number and decreasing or subtracting $15$ from the multiplication, we will get \[25\]. If we write this statement mathematically, we will get the below mathematical statement in terms of x.
$\Rightarrow 20x-15=25$
Adding $15$ both the sides, we get
$\begin{align}
  & \Rightarrow 20x-15+15=25+15 \\
 & \Rightarrow 20x=40 \\
\end{align}$
Finally, dividing both the sides by $20$, we get
$\begin{align}
  & \Rightarrow \dfrac{20x}{20}=\dfrac{40}{20} \\
 & \Rightarrow x=2 \\
\end{align}$
Hence, the required number is equal to $2$.

Note: After solving the equation, check the obtained solution in accordance with the information given for the required number. While obtaining the mathematical equation by writing the given statement in the above question mathematically, take proper care of the BODMAS rule. In the given statement, two mathematical operators are used, which are multiplication by $20$, and subtraction by $15$. According to the BODMAS rule, multiplication is performed before subtraction. So we have formed the equation as $20x-15=25$ and not $20\left( x-15 \right)=25$.