Iam terrible at math and i am so confused

In the diagram of circle o, what is the measure of zabc?

Which sum or difference identity would you use to verify that cos (180° - q) = -cos q? a.) sin (a -b) = sin a cos b – cos a sin b b.) cos (a -b) = cos a cos b – sin a sin b c.) cos (a -b) = cos a cosb + sin a sin b d.) sin (a + b) = sin a cos b + cos a sin b

Harry the hook has 7 1/3 pounds of cookie dough. she uses 3/5 of it to bake cookie. how much cookie dough does she use to make cookie?