Compute DOL for U.S. Steel

I am having trouble trying to figure out how to do this problem....I have looked around the site but the answers don't really show the steps I need to figure out this problem.

Units Sold	Total Variable Cost	Fixed Costs	Total Costs	Total Revenue	Operating Income (Loss)
60,000	120,000	50,000	170,000	360,000	190,000
80,000	160,000	50,000	210,000	480,000	270,000

a.) Compute DOL based on the following formula

DOL=%change in operating income/% change in units sold

b.) confirm that your answer is correct by recomputing DOL using this formula...

DOL=Q(P-VC)/Q(P-VC)-FC