PRACTICE The total cost, \( t \), of an online order is the cost of the items, \( c \), plus the cost of shipping. \( s \). (a) Write an equation to represent the total cost. (b) Solve the equation for the cost of the items. (c) Solve the equation for the cost of shipping.

The total cost can be represented by the equation \( t = c + s \). This equation reflects that the total cost \( t \) is the sum of the item cost \( c \) and shipping cost \( s \). To solve for the cost of the items, rearranging the equation gives you \( c = t - s \). This means that if you know the total cost and the shipping cost, you can easily find out how much the items cost. To find the cost of shipping, rearranging the original equation provides \( s = t - c \). This allows you to determine the shipping cost if you know the total and the cost of the items.