The JAR syllabus is limited to special cases in which the 1 degree of arc = 60 nm. These cases are; two points on the same meridian, two points on a meridain and anti-meridian, or two points on the equator.
But even with these we need to be careful in reading the question. Going north/south along a meridian does not change longitude, unless we pass over/under one of the poles. As we go over/under the poles there is of course an abrubt change of longitude. This change is not proportional to the distance flown.
For other cases such as two points on different meridans and different latitudes, the calulations require spherical geometry which is (thankfully) beyond JAR ATPL.