Question 1043532
(B)
{{{ a + r*( t-3 ) }}}
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Suppose 
{{{ a = 100 }}} cents
{{{ t = 20 }}} min
{{{ r = 10 }}} cents/min ( applies to {{{ t>3 }}} )
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Cost of call = {{{ 100 + 10*( 20 - 3 ) }}}
Cost of call = {{{ 100 + 10*17 }}}
Cost of call = {{{ 270 }}}
$2.70