# N13

QUESTION: Evaluate $\dfrac{3}{7}-\dfrac{6}{5}$.

ANSWER: To find a common denominator, multiply the denominators: $7\times 5=35$. To make the denominator of the first fraction 35, we need to multiply its top and bottom by 5:

$\dfrac{3}{7}=\dfrac{3\times5}{7\times5}=\dfrac{15}{35}$

To make the denominator of the second fraction 35, we need to multiply its top and bottom by 7:

$\dfrac{6}{5}=\dfrac{6\times7}{5\times7}=\dfrac{42}{35}$

Now we can do the subtraction. We get:

$\dfrac{15}{35}-\dfrac{42}{35}=-\dfrac{27}{35}$