Question 550207
There are 20 possible outcomes (you have 5 choices for the first digit and 4 for the second 5*4=20):
34 no 
35 no
36 yes
37 no

43 no
45 yes
46 no
47 no

53 no
54 yes
56 no
57 yes

63 yes
64 no
65 no
67 no

73 no
74 no
75 yes
76 no

Desired outcomes are multiples of 3. The quick way to see if something is a multiple of 3 is to see if its digits add up to a multiple of 3 (its a math trick). See the yes and no's above for which ones are multiples of 3.

So the ones we want are 6 and the total is 20

so 6/20 reduces to 3/10