Question 1156418
Let {{{ a }}} = the cost of an adult ticket
Let {{{ b }}} = the cost of a child ticket
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(1) {{{ 6a + 7b = 155 }}}
(2) {{{ 8a + 14b = 258 }}}
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Multiply both sides of (1) by {{{ 2 }}} and
subtract (2) from (1)
(1) {{{ 12a + 14b = 310 }}}
(2) {{{ -8a - 14b = - 258 }}}
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{{{ 4a = 52 }}}
{{{ a = 13 }}}
and
(1) {{{ 6a + 7b = 155 }}}
(1) {{{ 6*13 + 7b = 155 }}}
(1) {{{ 7b = 155 - 78 }}}
(1) {{{ 7b = 77 }}}
(1) {{{ b = 11 }}}
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$13 = the cost of an adult ticket
$11 = the cost of a child ticket
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check:
(2) {{{ 8a + 14b = 258 }}}
(2) {{{ 4a + 7b = 129 }}}
(2) {{{ 4*13 + 7*11 = 129 }}}
(2) {{{ 52 + 77 = 129 }}}
(2) {{{ 129 = 129 }}}
OK