I am coming to help! You want to know how to evaluate the expression \(\frac{4}{5}\frac{1}{6}\):
To subtract (or add) fractions, we have to create a common denominator. What does that mean? It means that the denominators of both fractions must be the same before we can actually do any subtraction. 4/5 and 1/6 are not fractions with common denominators, so we will have to manipulate the fraction such that both have a common denominator.
To do this, we must figure out the LCM (lowest common multiple) of both denominators in this expression. Normally, you could use a process to figure out the lowest common denominator, but we can actually use a shortcut here. If you are trying to find the LCM of two numbers that is 1 unit away from each other on a number line, then simply multiply both numbers together. This means that the LCM of 5 and 6 is 5*6, or 30:
This is the denominator that we want both fractions to have. Let's manipulate 4/5 first:
\(\frac{4}{5}*\frac{6}{6}\)  Notice that we are actually multiplying the fraction by 1, which does not change the actual value of the fraction. 
\(\frac{24}{30}\) 

Now, let's change the other fraction such that the denominator is 30:
\(\frac{1}{6}*\frac{5}{5}\)  Just like above, I am making the denominator to 30. 
\(\frac{5}{30}\) 
Now, let's subtracting the 2 fractions! It should be much easier now!
\(\frac{24}{30}\frac{5}{30}\)  When subtracting fractions, only subtract the numerator, but keep the denominator. 
\(\frac{19}{30}\)  19 and 30 are coprime, so the fraction cannot be simplified anymore. 
Therefore, \(\frac{4}{5}\frac{1}{6}=\frac{19}{30}\)