The equation that relates x and y :
y = kx , where k is the proportionality constant.
For given question,
y varies directly as x
Also, y= 12.4 when x= 4
So, for x = 1 the value y is,
y = 12.4/4
y = 3.1
As y is directly proportional to x, the equation that relates x and y is,
y = kx
where k is the proportionality constant.
We know that when two values or quantities are directly proportional to each other then one value decreases at the same rate that the other increases.
Therefore, the equation that relates x and y :
y = kx , where k is the proportionality constant
Learn more about the directly proportional here:
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