Which two ratios form a proportion?
a) 1 : 4 and 5 : 20
b) 1 : 4 and 20 : 5

c) 4 : 1 and 20 : 4
d) 4 : 1 and 4 : 20

a)1 : 4 and 5 : 20

Step-by-step explanation:

If a ratio is a proportion that means the

quantity on the left hand side is lesser than the quantity on the right hand side; it's a part of a whole, a small fraction.

Example of proportion ratios:

4 : 7

7 : 29

90 : 200

68 : 140

Example of non-prpotion ratios:

7 : 4

80 : 19

29 : 20

answer: option a.

step-by-step explanation:

you know that the quadrilateral opqr ( a four sided figure) is inscribed in circle. this means that all its vertices are on the circle.

then, by definition, the opposite angles of the quadrilateral are supplementary, this means that the sum of their measures is 180 degrees.

you can observe in the figure that the angles ∠opq   and the angle ∠orq   are opposite, therefore:

then, can be used to d to calculate the measure of ∠opq