Julia finds a texting plan that costs a flat fee of $20 per month for 120 texts, plus $.20 per text after that. Which cost function represents this scenario if x equals the number of texts exceeding 120 that Julia sends in a month?
Answer

C(x) = .20+ 120x

C(x) = 120 + .20x

C(x) = .20 + 20x

C(x) = 20+ .20x

Question

Julia finds a texting plan that costs a flat fee of $20 per month for 120 texts, plus $.20 per text after that. Which cost function represents this scenario if x equals the number of texts exceeding 120 that Julia sends in a month?
Answer
		
C(x) = .20+ 120x
		
C(x) = 120 + .20x
		
C(x) = .20 + 20x
		
C(x) = 20+ .20x

anonymous · Answer

C(x) = 20+ .20x

saifoo.khan · Answer

As you can see, that 20 is fixed amount you have to pay it.
And 0.20 is the slope here. This tells us, that how many texts you do, that much you have to pay.

If you compare it with y = mx + b
So you will find something like,

0.20x + 20