Final answer:
The question about the angle y in geometry seems to stem from a misunderstood concept, as the provided information pertains to physics and economics. The student likely has an isosceles triangle scenario, but without further details or a diagram, a specific solution cannot be given.
Step-by-step explanation:
The student is asking for assistance in finding the size of the angle marked y on a straight line with a given condition that CE = CF. Unfortunately, the provided information seems to be related to various physics and economics equations, none of which are related to the geometry problem at hand. However, to solve a similar geometry problem where a line segment EF is bisected by CE and CF, and based on the conditions provided (like CE = CF), it typically means that triangle CEF is an isosceles triangle, and the base angles (which one of them might be y) are equal. Without additional information about angles or lengths in the problem, or a diagram, it's not possible to provide a specific numerical answer. More information would be needed to solve this problem accurately.