You have 3 cards to be placed in the positions 1,2, 3.

let's see what the given information tell us:

A diamond is to the left of a spade.

So, the diamond cannot be on position 3, and the spade cannot be on the first one.

An eight is to the right of a king.

So, 8 cannot be the first, and K can not be the third.

A ten is to the left of a heart.

so, 10 cannnot be the third, and the heart cannot be first.

A heart is to the left of a spade.

the heart cannot be the third, and the spade cannot be first.

Since, the heart cannot be neither the first nor the third, it should be the second.

The spade cannot be the first, so it would be the third(the 2nd position taken by the heart.)

So, the diamond has to be the first.

Now, let's see the faces of the cards.

A ten is to the left of a heart(2nd), so it has to be the first.

the king cannot be the third, so is the second.

For the 8 we have left the third position.

The three cards are in order:

10 diamond/K heart/8 spade