A certain smartphone family plan costs $55 per month plus additional usage costs. If x is the number of cell phone used above the plan amount and y is the number of megabytes of data used above the plan amount, interpret the following expressions

a. 0.25x

b. 2y

c. 0.25x + 2y + 55

First thing to do, is organize in your mind what is asked of the problem. Since the problem talks about total cost, then you are dealing with monetary units of measurement. Next, you investigate on the variables given and what they represent. Looking at the following expressions, I could not immediately get a hint on what these terms stand for. But for letter c, I deduced that that would be the overall equation representing the total cost.

The first term, 0.25x, must be the cost of the phone units purchased under the plan. That means each cellphone unit used costs $0.25 each. The second term, 2y, must be the cost of data used by the plan. So, that means each megabyte used up costs $2. These two costs must be what is referred to by the additional costs. Lastly, the last term, '55'. is the fixed cost when you subscribe to the amount per month. Hence, the equation in letter C represents the total cost per month.