Sam downloaded four applications for $2.99 each to her cell phone. The remaining applications that Sam purchased cost $1.99 each.

If she downloaded x total applications, which of the following equations can be used to find how much Sam spent on cell phone application downloads?

A: y = 11.96(x - 4) + 1.99
B: y = 1.99x + 11.96
C: y = 11.96x + 1.99
D: y = 1.99(x - 4) + 11.96

2 answers

D. 1.99(x-4) + 11.96
Because you can figure out the total cost of the four costing $2.99 (11.96), that has to be added to the other half of the equation. Simply multiplying 1.99 by x would include all apps instead of just the remaining (x-4).
Or you could say that each costs $1.99 with the first 4 costing a dollar more
so ..

y =1.99x + 4

that would be the simplest equation,
Too bad they don't have it