Question

Find the unknown number: $\_\_\_\_\_-\dfrac{3}{7}=\dfrac{3}{7}$ .
(a) 0
(b) 1
(c) $\dfrac{3}{7}$
(d) $\dfrac{6}{7}$

Answer 1

Hint: Let the unknown number be x. So, our equation comes out to be $x-\dfrac{3}{7}=\dfrac{3}{7}$ . Then solve the equation by keeping the x on one side of the equation and taking all the other terms to the other side and solve to get the value of x.

Complete step-by-step answer:
Let the unknown number be x. So, the equation given in the question becomes:
$x-\dfrac{3}{7}=\dfrac{3}{7}$
So, the equation we get is a linear equation in one variable x.
Now we will take $\dfrac{3}{7}$ on the left-hand side of the equation to the other side. On doing so, the sign changes, i.e., it gets added to the term on the right-hand side of the equation.
 $x=\dfrac{3}{7}+\dfrac{3}{7}$
Now, both the terms on the right-hand side are fractions with their denominators 7. As both have 7 as the denominator, the lowest common multiple of the denominator is 7 itself. So, if we take the LCM of denominator and make the required changes, we get
$x=\dfrac{3+3}{7}=\dfrac{6}{7}$
Therefore, the unknown number is $\dfrac{6}{7}$ . Hence, the answer to the above question is option (d).

Note:The key steps of solving the problem are taking LCM and performing the arithmetic operations, so don’t make a calculation error in these steps. It is also important that you don’t forget to change the sign when moving the terms from one side of the equation to the other. There is a possibility that you might miss the - sign in the question and choose option (a) 0 as the right answer. So, be careful not to jump into conclusions that will cost you marks.