Its the connection between those numbers
The measure of a central angle is equal to measure of a minor arc. That makes m<GEH=17x+12. By the Vertical Angles Theorem, m<GEH and m<IEF are equal to each other (m<GEH=17x+12=m<IEF). By the same theorem, m<FEG and m<IEH are also equal (m<FEG=8x-7=m<IEH). The angles in a circle must all add up to 360 degrees, 2(17x+12)+2(8x-7)=360. Solve for x, then plug x into the equation for m<IEF.
Hope this helps!
When two fractions have the same denominator, you can compare which fraction is greater by just comparing the numerators.
For example, if you have 2/5 and 3/5, the denominators are the same. So you can just look at the numerators. 3 is greater than 5, so 3/5 is greater than 2/5.
The reasoning to this is that the two numbers are divided by the same number (5), so you can compare the original numbers (numerators).
The answer is option c- 68°