The sum of the three angles of a triangle is always 180°. Tha is
(first measure) + (second measure) + (third measure) = 180°
Subtract the first two terms of this equation and you have
(third measure) = 180° - (first measure) - (second measure)
a. third measure = 180° - 45° - 55° = 80°
b. third measure = 180° - 50° - 40° = 90°
c. third measure = 180° - 110° - 35° = 35°
we know that
cup of flour is used to make
dinner rolls.
Part a) How much flour is needed to make one dinner roll?
by using proportion

therefore
the answer Part a) is
To make one dinner roll is needed
cup of flour
Part b) How many cups of flour are needed to make 3 dozen dinner rolls?
Multiply the value obtained in part a) by 
so


therefore
the answer Part b) is
To make
dozen dinner rolls are needed
cup of flour
Part c) How many rolls can you make with 5 2/3 cups of flour?

by using proportion

therefore
the answer part c) is
rolls
I think the answer should be B.
You cant simplify that fraction
6(7 - 2)
6(5)
Check:
7*6 = 42
2*6 = 12
42-12 = 30 = 6(5) :)