Question 1111103
Let {{{ y }}} = pounds of M&Ms left in bowl
Let {{{ x }}} = length of time in hrs he has been eating
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His rate of eating is {{{ 28/7 = 4 }}} pounds/hr
[ pounds of M&Ms in bowl ] / [ rate of eating them ] = [ time to eat them ]
{{{ 28/4 = 7 }}} hrs
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I have given myself the point ( 7, 0 ) on the line
( there is zero M&Ms left in bowl after {{{ 7 }}} hrs )
and for slope, {{{ m = -4 }}} 
( after each hr, there is less in the bowl )
{{{ y = m*x + b }}}
{{{ y = -4*x + b }}}
{{{ 0 = -4*7 + b }}}
{{{ b = 28 }}}
{{{ y = -4x + 28 }}}
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x-intercept:
( x, 0 ) 
{{{ 0 = -4x + 28 }}}
{{{ 4x = 28 }}}
{{{ x = 7 }}}
( 7, 0 )
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y-intercept:
( 0, y )
{{{ y = -4*0 + 28 }}}
{{{ y = 28 }}}
( 0, 28 )