Question 1018257
Let {{{ A }}} = attendance /day
Let {{{ p }}} = price of admission 
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When price of admission stays at $11:
{{{ A = m*p + b }}}
(1) {{{ 100 = m*11 + b }}}
When price drops to $6:
(2) {{{ 1700 = m*6 + b }}}
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Subtract (1) from (2)
(2) {{{ 1700 = m*6 + b }}}
(1) {{{ -100 = -m*11 - b }}}
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{{{ 1600 = -5m }}}
{{{ m = -320 }}}
and
(1) {{{ 100 = m*11 + b }}}
(1) {{{ 100 = (-320)*11 + b }}}
(1) {{{ 100 = -3520 + b }}}
(1) {{{ b = 3620 }}}
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The equation is:
{{{ A = -320p + 3620 }}}
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check:
( 11, 100 )
{{{ A = -320p + 3620 }}}
{{{ 100 = -320*11 + 3620 }}}
{{{ 100 = -3520 + 3620 }}}
{{{ 100 = 100 }}}
and
( 6, 1700 )
{{{ A = -320p + 3620 }}}
{{{ 1700 = -320*6 + 3620 }}}
{{{ 1700 = -1920 + 3620 }}}
{{{ 1700 = 1700 }}}
OK