I’m pretty sure that a is the answer
Using Pythagoras in the first question
c=

which is approximately 16.5
for the second question
we also use Pythagoras

If you use a table you see all the fractions next to each other and you see what did I do the get from this fraction to this fraction.
Answer:
12/16
Step-by-step explanation:
multiply 3/4 in the numerator and denomanator by 4 and you get 12/16