I need help with a word problem for a quadrilateral inscribed in a circle. It's as follows:

Measure of angle D = 75, measure of minor arc AB = x^2, measure of minor arc BC = 5x, and the measure of minor arc CD = 6x. Find x and the measure of angle A.

The answer is x=10 and m<A = 55. I just need the method used to come to that answer.

Thanks in advance.