Question 1073977
y, monthly cost
x, minutes of time


{{{y=0.15x+12}}}

{{{0.15x+12<=30}}}

{{{0.15x<=18}}}

{{{x<=(3*6)/(3*5*0.01)}}}

{{{x<=(6/5)100}}}

{{{highlight(x<=120)}}}



---
check:
{{{0.15*120+12}}}
{{{18+12}}}
{{{30}}}<pre>, the given maximum cost</pre>