Help me please I am confused on this

Step-by-step explanation:

Given:

p = f(n) = 30n - 450

We will find n in terms of p

p = 30n - 450

p + 450 = 30n ⇒ divide both sides by 30

So,  n = p/30 + 450/30

∴ n = p/30 + 15

∴ n = f⁻¹(p) = n = p/30 + 15

At p = $500

∴ n = 500/30 + 15 = 31.67

n ⇒ number of cakes must be integer number

So, to make a profit at least $500, the number of cakes that Joanna must sell = 32 cakes