Question 269262
Let {{{m}}} = number of minutes used
Let {{{c}}} = cost of plan
1st plan:
{{{c[1] = 30 + .09m}}}
2nd plan:
{{{c[2] = .14m}}}
The 2 costs are the same when
{{{30 + .09m = .14m}}}
{{{.05m = 30}}}
{{{m = 600}}}
after 600 min the costs of the plans are the same
check:
{{{c[1] = 30 + .09m}}}
{{{c[1] = 30 + 54}}}
{{{c[1] = 84}}}
and
{{{c[2] = .14m}}}
{{{c[2] = 84}}}
OK