Can anybody me out? i think i know what i am doing but, can anyone explain it in detail?

Sqrt{a} × sqrt{b} = sqrt{ab}
and when you have a mix of numbers andw variable, i.e '6' and 'x', then just multiply numbers and multiply x's and sqrt the product of these both:
sqrt{3x} × sqrt{6x} × sqrt{14x}
= sqrt{3×6×14×x×x×x}
= sqrt{252x^3}
[this can be simplified to: 6x(sqrt{7x})]

3/0.5 = 6
6 x 10 = 60
D