I need help solving this radical operation√(90) - √(40)

Question

I need help solving this radical operation
`√(90) - √(40)`

Answer 1

`\begin{gathered} √(90)-√(40)=√(9*10)-√(4*10) \\ \text{ =}√(9)*√(10)-√(4)*√(10) \\ \text{ =3}√(10)-2√(10) \end{gathered}`

taking √10 common,

`√(10)(3-2)=√(10)`