how to do soluitions using formulas and how to substituite the equations in formulas

first, see the question clearly and note the key points[find what is asked in the question]. then analyse the data u have in question and write down the data.  if you have memorized all formulae from your book it will be really easy to the formula in your answer. So it is important that you understand the content and memorize the formulae.

I hope u like my tip.