Consider the utility function U(x,y) = y√x Draw the indifference curve for U= 10, U=15, U=20.

My knowledge of algebra has deteriorated over the last few years of being out of school and I am really unsure of how to answer this.

The X value is going up in the standard 1 to 10.
Hint: This suggests $y=\dfrac{U}{\sqrt{x}}$  

so draw the three curves in the usual way


$y=\dfrac{10}{\sqrt{x}}$; three of the points are $(1,10)$ and $(4,5)$ and $(9,3.333)$
$y=\dfrac{15}{\sqrt{x}}$; three of the points are $(1,15)$ and $(4,7.5)$ and $(9,5)$
$y=\dfrac{20}{\sqrt{x}}$; three of the points are $(1,20)$ and $(4,10)$ and $(9,6.667)$