2.80 is 2.80: you do not need to ise proportions or anything to "find" it!
x/y= 2.8
You find central angle by using proportions. Part/Whole = x/360 Then, cross multiply and divide.
so when you find your answer you can check it by using multiplication.
You can find a missing denominator if you know something that the fraction is equal to. Then you can find the missing denominator through cross multiplication.
The means-extreme property of proportions is the method that allows you to cross multiply an equation to find the answer. An example would be, if a/b = c/d then ad = bc.
16
See related link below to find help on proportions
tree diagram
Multiplication
With repeated multiplication.
What advantages did the Romans find in using a cross vault instead of a barrel vault?
Using your calculator will give an answer of 11/100 or 0.11