Answer:
y = kx
Step-by-step explanation:
Y is directly proportional to x if the relation can be written using the equation ...
y = kx . . . . . for some constant k
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Note that k may be positive or negative. The graph of this equation is a straight line through the origin.
The value of k can be found from corresponding values of x and y using ...
k = y/x
This is also another way to express the fact that x and y are proportional.