Calculating equity when you have a drawing hand and you know you're behind is fairly simple and looks exactly like your example with 98. As for the second example with T5... this is much more tricky since you're ahead most of the time and therefore you have to compare the strength of your hand vs. the entirety of villain's perceived range. This is something that's hard to do on the fly, but it comes with experience and you can improve by working both with equity calculators and other types of poker software.

Here's an article that may interest you and make this whole thing clearer: Poker Odds Calculator

You've got the math correct, but alas, almost nothing in poker is as simple as "This is exactly how many outs I have". In the 98 example, what if V has AK, then your Q outs are no good. Or If he has JJ, he will hit a full house sometimes you make your flush. So like Matt said, you're learning the math, but that's the beginning of the calculation.

So I have to calculate each range to make a decision?
For my example it's a easy call but with your example with AK or JJ its something to think about to fold?

If we had infinite time and a strong love of math, then yes, you could actually factor in all his possible hands, the % he has each one, etc. But in real life, we mostly fall back on ideas like, "Don't chase a SD when there's a FD out there or the board is paired," which takes into account that some of our outs are dirty. When facing serious levels of aggression vs a good player, I will do some serious shorthand math like, "I'm getting 2 to 1, but if he has a set or 2p he'll get there some % of the time, so it's more like 2.5 to 1." There's no way that my math is actually exact, but it helps acknowledge that even if I hit, I still won't win every time.

So if you thought were getting 2-1 like in your example and had exactly those odds, you should still fold. You always need a wee bit of overlay.