What is distance=12mi; time=2h; rate

This race was first held in 1953 on august 16th. every decade the race finishes with a festival. how many years is this?

Worth 30 points! in this diagram, both polygons are regular. what is the value, in degrees, of the sum of the measures of angles abc and abd?

X/y + 4y/x divided by x/y - 2y/x explain as in depth as you can how you simplfied the fractions. i don't know where to start on this : /