Question

f y varies directly as x and y is 6 when x is 72, what is the value of y when x is 8?

Answer 1

`y varies directly as x`:
This means that y is in a direct relationship with x,
y=x
But they may differ by some factor k, a `constant of variation`,
y=kx

So we have our relationship,\[\Large y=kx\]We'll plug in the given numbers to solve for the constant k,\[\Large y=6,\qquad x=72\qquad\to\qquad 6=k(72)\]k=?