Answer D
f(x)=3x if 0 <= x <= 10
f(x)=15x-120 if x > 10
Step-by-step explanation:
Hello,
The first 10GB of data he uses costs $3 per GB
so we can write
if 0<=x<=10 f(x)=3x
and f(10)=3*10=30
and once he exceeds the 10Gb the company charges $15 for each GB
so if x >10 f(x)=15x+b where b is a real
And f(10) should be 30 so 15*10+b=30 <=> b = 30-150=-120
so f(x) = 15x-120
hope this helps
