Question 504009
Let {{{a}}} = number of salads bought
Let {{{b}}} = number of cartons of milk bought
given:
(1) {{{ a + b = 8 }}}
(2) {{{ 275a + 80b = 1615 }}}  (in cents)
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Multiply both sides of (1) by {{{80}}} and
subtract (1) from (2)
(2) {{{ 275a + 80b = 1615 }}} 
(1) {{{ -80a - 80b = -640 }}}
{{{ 195a = 975 }}}
{{{ a = 5 }}}
and, since
(1) {{{ a + b = 8 }}}
(1) {{{ 5 + b = 8 }}}
(1) {{{ b = 3 }}}
5 salads were bought
3 cartons of milk were bought
check answer:
(2) {{{ 275a + 80b = 1615 }}} 
(2) {{{ 275*5 + 80*3 = 1615 }}} 
(2) {{{ 1375 + 240 = 1615 }}}
(2) {{{ 1615 = 1615 }}}
OK