Ratio formula is needed

Question

I have a simple match problem.

When X is 122 then Y is 0.

When X is 0 then Y is 1.

I need a formula so whenever I change the Y, then X should change accordingly.

As you can see, Y goes from 0.0 to 1.0. Then X goes from 122 to 1.0.

Answer 1

A simple ratio formula will not work. You will need a relation of the type

y = mx + b

You have 2 points (x,y):

(122,0)

(0,1)

Find the slope.

m = (1 - 0) / (0 - 122) = -1/122

y = (-1/122)x + b

Get b from either point. Using (0,1),

1 = (-1/122)(0) + b

b = 1

y = (-1/122)x + 1

Test this answer. When x=0, it gives y=1 (good). When x=122, it gives y=0 (good).