Forming equations using proportion by Boxed Rockets

Form Equations to Represent the Following

Question 1:

y is inversely proportional to x, when x = 9, y = 8

y = \frac{72}{x}

Question 2:

y is inversely proportional to x, when x = 1, y = 15

y = \frac{15}{x}

Question 3:

y is directly proportional to x, when x = 2, y = 20

y = 10 x

Question 4:

y is directly proportional to x, when x = 10, y = 110

y = 11 x