Answer:
1. y = 90x
x: the amount of companies to start
y: The total amount it will cost.
2. y = 30x
y: the total income
x: the amount of sweaters being sold.
The answer to the last question(I think would be):
cost: $30
income: $60
as:
equation to find cost = y = -15x
equation to find income = y = 30x