Write as a monomial in standard form: (-x^2y^3m)^5

Lisa has three classes that each last 50 minutes. what is the total number of minutes of the three classes

Acertain volume of water contains 100000 hydrogen atoms and 50,000 oxygen atoms how many hydrogen atoms are in a volume of water containing 4 million oxygen atoms

Square a has a side length of (2x-7) and square b has a side length of (-4x+18). how much bigger is the perimeter of square b than square a?and show all work! you so