First of all, you can simplify the 4 at the numerator and the 14 at the denominator (they're both multiple of 2):

Now, rationalize a denominator means that you have to get rid of the square root, in order to have an integer denominator.
To do so, remember that you can always multiply any number by 1 without changing its value, and you can always think of 1 as a fraction where numerator and denominator are equal:

Answer:
100°
Step-by-step explanation:
the total of all angles around O on one side of AD is 180° (as that would represent a half-circle).
and the sum of the arc angles AB + BC + CD covers the whole 180°.
so, we have
180 = 55 + BC + 25
180 = 80 + BC
BC = 100°
100 and 101
the two integers are n and n+1. this means that 2n+1=201. n=100 and n+1=101