im desperate for an answer please help ASAP

Question

A construction supply store sells steel bars for a certain price per kilogram.
No matter how much steel is ordered, the company adds on the same delivery charge.
The cost for an order of 100 kilograms of steel bars is $230.
The cost for an order of 150 kilograms of steel bars is $320.
Write an equation for the cost of an order of steel bars
(y) in terms of the weight of steel bars ordered
(x).
Show or explain how you found your equation

Answer 1

The extra 50 kg cost  (320-230)=90

Per kg cost = 180/100= 1.80.

100 KG variable cost = 180

fixed cost = delivery cost = 230-180 = 50.

y=1.8x+50