Forming equations using proportion by Boxed Rockets

Form Equations to Represent the Following

Question 1:

y is directly proportional to x, when x = 9, y = 81

y = 9 x

Question 2:

y is directly proportional to x, when x = 1, y = 7

y = 7 x

Question 3:

y is inversely proportional to x, when x = 6, y = 8

y = \frac{48}{x}

Question 4:

y is inversely proportional to x, when x = 10, y = 12

y = \frac{120}{x}