We can first add up the cards so we know how many we have in all:
16 + 16 + 18 = 50 cards
We can do this a little bit easier if we get the "16"-cards in one number total.
16 + 16 = 32

= 32 x 2 =

50 x 2

= 64 : 2 = 32 %
100
We did just divide the % of two types cards on 2, so we get the %-chance of 1 type card.
I am not quite sure, but I think that 32 % is the correct answer.
Answer:
4 hours
Step-by-step explanation:
Since we know he travels at a rate of 1:7.5 all we have to do is divide 7.5 by 30. Do you use proportions? You can set this up as a proportion and the find answer easily.
1
Now we cross product.
7.5 multipled by x =7.5x
1x30=30
so now we have
7.5x=30
Now we have to divide 7.5 on both sides which gives us
x=4