Question

write a latter to younger brother advicing him to take care of this helth

Answer 1

i am not sure of the format so just check it out.
I will give some points for the main content. Frame the letter properly

Dear Raju,
Hope you are fine. From your last letter I got to know that you had high fever.
You must take care of your health and also be hygienic and stay away from diseases.
Be careful about the food you eat and eat only healthy food.