Question

The cost, C, in millions of dollars of producing T million tons of steel is modeled by the equation C = 220T + 1890.

Answer 1

C = 220T + 1890.

Solve the equation for T.

220T = C - 1890

T = C/220 - 8.6

The steel produced is expected to be sold at a price of $310 per ton.

310 $/ton is a rate or slope. Write a linear equation where x is tons of steel produced and y is selling price of the steel.

y = 310x

Write and solve an equation to find the amount of steel produced if the selling price is equal to the cost of production.

* Here, note that the cost of production and tons of steel in the first equation is in the millions.  The equation we just wrote for the selling price was in x tons of steel. This only matters in regards to the units you specify because; million/million = 1

The unit multiplier of all variables must be specified as same. Either everything is in millions or not.

Here, I'll leave everything in millions, change x (tons of steel) to T (mill tons steel) and "y" to "S" in million dollars selling price.

S = 310T

Set equal to Cost equation.

220T + 1980 = 310T

Solve for T, million tons of steel produced.

1980 = 310T - 220T

1980 = 90T

T = 1980/90

T = 22 million tons steel produced