Question

Abi has 20 cents. Se bought x pencils for 3 cents each. If y equals the number of cents left, write an equation that shows the dependence of y on x. What is the domain of the function?

Answer 1

function= y=20-3x

Domain= 1,2,3,4,5,6

Answer 2

The function would be:

• y = 20 - 3x

Since y should be positive or zero:

• 20 - 3x > 0
• 3x < 20
• x < 7

So x can get values from 0 to 6.

The domain is:

• x∈N, x = [0, 6]