Find the probability of drawing a 10, replacing it, and drawing an ace.

Assuming that you're talking about a standard deck of 52 cards, there are 4 tens and 4 aces.

So, at the beginning, you have probability 4/52=1/13 to draw a ten.

You replace, and you have an identical probability to draw an ace (you still have 4 favourable cases over 52 total cases).

Multiply the two probabilities to find the

if x = 1, then the answer is 3.5