You cannot add or subtract fractions with different denominators. To make it possible to subtract, find the lowest common multiple of the two denominators.

The LCM of $8$ and $6$ is $24$.

$\text{Multiply }\frac{3}{8}\text{ by }\frac{3}{3}\text{ and }\frac{1}{6}\text{ by }\frac{4}{4}.$

This will make the denominators the same.

$\frac{3}{8}\cdot \frac{3}{3} = \frac{9}{24} \ \ \ \ \ \ \ \ \ \frac{1}{6}\cdot \frac{4}{4}=\frac{4}{24}$

Now you can subtract the numerator of the first term from the numerator of the second.

$\frac{9}{24}-\frac{4}{24}=\frac{5}{24}$

You don't need to change the denominator for this one. However, you will end up with a fraction greater than $1$. You will need to change it to a mixed number.

This problem can be solved in the same way as part (a).