Proportional relationships shows the relationship between two or more variables where their ratios are equivalent in a given expression. It is majorly a direct relation, which implies that as the value of on variable increases, the value of the other variable also increase.
From the expressions given, the first shows a good proportion between the variables given.
90. The measure of an inscribed angle is half of that of the measure of its arc, and the measure of the angle corresponding with arc a is 45. 45*2 is 90, so 90 is the measure of arc a.
