Question 140875
Let {{{a}}}=introductory minutes
Let {{{b}}}= additional minutes
{{{a + b = 35}}}
{{{b = 35 - a}}}
{{{16a + 11b = 495}}}
{{{16a + 11*(35 - a) = 495}}}
{{{16a + 385 - 11a = 495}}}
{{{5a = 495 - 385}}}
{{{5a = 110}}}
{{{a = 22}}}
{{{b = 35 - a}}}
{{{b = 35 - 22}}}
{{{b = 13}}}
22 minutes were billed at introductory rate
13 minutes were billed at additional rate
check:
{{{16a + 11b = 495}}}
{{{16*22 + 11*13 = 495}}}
{{{352 + 143 = 495}}}
{{{495 = 495}}}
OK