Forming equations using proportion by Boxed Rockets

Form Equations to Represent the Following

Question 1:

y is inversely proportional to x, when x = 2, y = 8

y = \frac{16}{x}

Question 2:

y is directly proportional to x, when x = 5, y = 40

y = 8 x

Question 3:

y is directly proportional to x, when x = 4, y = 28

y = 7 x

Question 4:

y is inversely proportional to x, when x = 10, y = 7

y = \frac{70}{x}