Question 84104
{{{t[i]}}} = time on the internet in minutes
{{{t[p]}}} = time on the phone in minutes
{{{r[i]}}} = rate for internet use in dollars/minute
{{{r[p]}}} = rate for phone use in dollars/minute
{{{b}}} = total bill for phone and internet
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{{{b = t[i]*r[i] + t[p]*r[p]}}}
{{{500*r[i] + 100*r[p] = 88}}}
{{{400*r[i] + 150*r[p] = 76}}}
Multiply the 1st equation by 3 and the 2nd by 2
{{{1500*r[i] + 300*r[p] = 264}}}
{{{800*r[i] + 300*r[p] = 152}}}
subtract the 2nd from the 1st
{{{700*r[i] = 112}}}
{{{r[1] = .16}}}
So, the rate for internet use is 16 cents/minute