All these cases represent experiments whose outcomes are all equaly likely. What we mean is that the cards have all the same probability of being dealt (1/52), and all the spaces of the spinner have the same probability of being landed into (1/5).
These probabilities are computed as 1 over all the possible outcomes.
(a) If you want a heart card and a five, you want the 5 of hearts. So, only one card would satisfy your request, and thus you have probability 1/52 of dealing the 5 of hearts.

(b) There are four 10s and four Jacks in the deck, so 8 cards satisfy your request. With probability 8/52, you'll be dealt a Jack or a 10.

(c) You have two "good" outcomes out of 5, so your probability is 2/5.

30 students
14 have no siblings
that leaves 16 with siblings
6 have brothers and 12 have sisters which = 18 so 2 of the students have both a brother and a sister
2/30 students have a brother and a sister
1/15 chance
I never took geometry but good luck and gh= 3
The answer will be
f(3)=3(3)+7
=9+7
=16