Question 987634
Let {{{ a }}} = the cost of a pen
Let {{{ b }}} = the cost of a pad
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(1) {{{ 10a + 15b = 26 }}}
(2) {{{ 5a + 10b = 16 }}}
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Multiply both sides of (2) by {{{ 2 }}}
and subtract (1) from (2)
(2) {{{ 10a + 20b = 32 }}}
(1) {{{ -10a - 15b = -26 }}}
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{{{ 5b =6 }}}
{{{ b = 6/5 }}}
and
(2) {{{ 5a + 10*( 6/5 ) = 16 }}}
(2) {{{ 5a + 12 = 16 }}}
(2) {{{ 5a = 4 }}}
(2) {{{ a = 4/5 }}}
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A pen costs $.80
A pad costs $1.20
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check:
(1) {{{ 10a + 15b = 26 }}}
(1) {{{ 10*(4/5) + 15*(6/5) = 26 }}}
(1) {{{ 40 + 90 = 5*26 }}}
(1) {{{ 130 = 130 }}}
OK