An example should make this clear.
If $50 is 40% what is the value of the whole amount?
Answer:- Whole amount = 100^%
By proportion this = (100/ 40) * 50
= 2.5 * 50
= $125 (answer)
Answer:
A. 5.8
Step-by-step explanation:
From the given graph d has two coordinates;
the first coordinates of d = (0, 0)
the second coordinate of d = (-3 , -5), that is x = -3 when traced up and y = -5 when traced horizontal
The distance between the two coordinates = distance of d;

Option A is correct
In linear models there is a constant additve rate of change. For example, in the equation y = mx + b, m is the constanta additivie rate of change.
In exponential models there is a constant multiplicative rate of change.
The function of the graph seems of the exponential type, so we can expect a constant multiplicative exponential rate.
We can test that using several pair of points.
The multiplicative rate of change is calcualted in this way:
[f(a) / f(b) ] / (a - b)
Use the points given in the graph: (2, 12.5) , (1, 5) , (0, 2) , (-1, 0.8)
[12.5 / 5] / (2 - 1) = 2.5
[5 / 2] / (1 - 0) = 2.5
[2 / 0.8] / (0 - (-1) ) = 2.5
Then, do doubt, the answer is 2.5
(1) the diameter is 20 inches whats the radius? And whats the circumference?
Radius is half the diameter, Answer: 10 inches
Circumference is pi times the radius, Answer: 10π inches
I won't bother with the approximation, though this one is easy, 31.4159 inches. I'll leave the rest of the calculator work to you if necessary.
(2) the diameter 11 inches whats the radius? And whats the circumference?
Radius half, Answer: 5.5 inches. Circ: 5.5π inches
(3) the diameter 3.5 inches whats the radius? And whats the circumference?
Radius, 1.75 inches. Circ: 1.75π inches
800+4000+194
800+4000=4800
4800+194=4994
answer:4994