How do you solve $ \dfrac{a}{5} - 2 = 9 $ ?

Hint: To solve this problem, we need to take Least common multiple. After that, it involves normal evaluation and simplification. To solve this problem, we can look for a number of methods but here I suggest you a method which you can solve within a few seconds.

Complete step-by-step answer:
Here we need to find the value of $ a $ . Use LCM to solve this question,
 $
  \dfrac{a}{5} - 2 = 9 \\
  \dfrac{{a - 10}}{5} = 9 \\
  a - 10 = 45 \\
  a = 55 \;
  $
Alternative method,
 $
  \dfrac{a}{5} - 2 = 9 \\
  \dfrac{a}{5} = 9 + 2 \\
  a = 11\times 5 \\
  a = 55 \;
  $
So, the correct answer is “ a = 55”.

Note: Least common multiple is a method to find the least multiple of the given numbers. For instance, if we were told to find the LCM for the numbers $ 3,9,27 $ . First, we have to look for the large number, which is 27 and then we have to check if the number 27 is divisible by the other two numbers or not. If it is divisible then it is our LCM for this number. If not, then we have to multiple the larger number by 2 and check the above-mentioned conditions. We have to do it until we get the LCM of the numbers. In the case of $ 5,12,15 $ , $ 15 $ is not divisible by $ 12 $ and now multiply $ 15 $ by 2 which is $ 30 $ . Still, we didn’t get the answer so repeat this process until we get the LCM. Here, in this problem $ 15\times 4 = 60 $ is the LCM.