https://web2.0calc.com/questions/help-please-gt-lt
https://web2.0calc.com/questions/please-help-asap_57
These have been answered already; the first one in great detail. It’s no good just repeating the question. You need to be more precise in stating what you don’t understand and where you start to lose the plot.
If your teacher wants the result in a different form you need to say what that different form is.