Question

What should be added to \[39.587\] to give $80.375$ ?

Answer 1

Hint: Consider the number which is to be added to \[39.587\] be $x$. Using the statement in the question, form an equation which will help us to solve this question. Also, use the transposition method to solve this question.

Complete Step by Step Solution:
According to the question, we know that we have to find the number which when added with \[39.587\] gives the sum as $80.375$. Therefore, let the number which is to be added to \[39.587\] be $x$.
Now, making use of the statement given in the question, we get the equation as –
$ \Rightarrow 39.587 + x = 80.375 \cdots \left( 1 \right)$
In the above equation, if we get the value of $x$, then, we will also get the answer to this question.
To find the value of $x$, we have to use the transposition method, the transposition method is the method in which the number is shifted to another side of the equation but its function or sign changes.
If any number is performing addition then after using the transposition method it gets shifted to another side of the equation and its sign or function changes to subtraction and if it performs subtraction, then when it is shifted to another side it will perform addition.
Similarly, if the number performs multiplication, then after using the transposition method, it will perform division and change its side and if it is performing division, then, it will perform multiplication.
Therefore, in the equation (1), we have to shift $39.587$ to another side so, after using transposition method, it gets shifted to another side of the equation but its sign changes to subtraction –
$
   \Rightarrow x = 80.375 - 39.587 \\
   \Rightarrow x = 40.788 \\
 $

Hence, when $40.788$ is added to $39.587$ gives the sum as $80.375$

Note:
We also use the cross – multiplication method to find the unknown terms in the equation, but it is used when there is multiplication or division in the equation. This method cannot be used in these types of equations.