First, we must find the constant of proportionality, k, shared between y and x. Since they're directly proprtional, we have
y = kx.
Given that y is 72 when x is 6, we can substitute these values into the equation and solve for k.
72 = 6k
k = 72/6 = 12
Now, since k = 12, we can substitute this into the equation and have
y = 12x, which is the direct variation equation relating x and y.
Now, using this equation, the value of y when x is 10 is equal to y = 12(10) = 120.
Answer:
B. y = 12x ; 120
