Help and check?

First one    

We have a 45 - 45 - 90    right triangle

The sides opposite the 45°  angles are equal

Therefore.....2√10  = √40  = x

Using the Pythagorean Theorem

√ [  ( √40)^2  + (√40)^2 ]   =  √ [40 + 40]  = √80  =  4√5  =  y

Second one

We have a 30 - 60 - 90     right triangle

y  is  opposite the 30° angle ....its length is    30/√3

x is opposite the  90° angle....it has twice the length of x  =  60/√3

Third one

Another 30 - 60 -90  right triangle

The side opposite the  30°   angle has (1/2)  the length  of 14√3  =    7√3   =  y

The side opposite the  60°  angle  has a length of √3  times 7√3  =  7√3 *√3  = 7 * 3  =  21 = x

Your answer to the last one is correct   ....good job   !!!!