PLEASE HELP I will mark as Brainlist
1.simplify : (4b+5c)^2 - (4b-5c)^2

2.factorise: 75a^2 b^2 - 27x^2 y^2 and x^2-3x-20

3.find the square: (a+2b+3c)
find the root of (3x-4y)

4.solve: x-30% of x=RS.140

5.resolve into factors: x^4 - 16 y^4 b, x^2-9x+2.

6.A sick person has to take three types of medicine. He takes type -x in every 3hrs, type-y in every 4 hrs, type -z in every 6 hrs. if he takes all types of medicines at the same time at 6:00 am, at what time does he take all these types of medicine, again at time?