In order to determine the number of boys in the class, first, we set-up an algebraic equation. Let x = number of boys in the class. The equation is then: x + 4x = 45. This is because the number of girls is 4 times greater than the number of boys. After solving the algebraic equation, it is then determined that there are 9 boys in the Chemistry class.
4 sqrt(400) / 4 sqrt(5)
sqrt(400) =20
4 *20
--------
4 sqrt(5)
the 4's on the top and bottom cancel
20
--------
sqrt(5)
I was taught never to leave a sqrt in the denominator
so you need to multiply by sqrt (5) in the numerator and the denominator
20* sqrt(5)
--------
sqrt(5)* sqrt(5)
20* sqrt(5)
--------
5
= 4 sqrt(5)
