multiplying radicals sqrt(ab)= sqrt(a)*sqrt(b) and vice versa if you have a number infront you just multiply it in so 5sqrt(a)*2sqrt(b) = 10sqrt(ab)

dividing radicals sqrt(a/b)=sqrt(a)/sqrt(b) and vice versa if you have a number in front you just divide similar to above like 10sqrt(a)/2sqrt(b)= 5sqrt(a/b)

adding radicals the number under the sqrt must be the same so 2sqrt(3)+3sqrt(3)=5sqrt(3) but

2sqrt(3)+3sqrt(2) doesnot =5sqrt(3) this is the same for subtracting but instead of adding the number in front you subtract

As for simplyfying just remember to look for multiplication adn division as that is the easiest and then do the adding and subtracting and if the number in the sqrt is not the same then you cannot do anything unless it is multiplying or dividing