Question 995988
Let {{{ a }}} = the cost of 1 pencil
Let {{{ b }}} = the cost of 1 book
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(1) {{{ 6b + 10a = 17000 }}}
(2) {{{ 3b + 22a = 17000 }}}
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Multiply both sides of (2) by {{{ 2 }}}
and subtract (1) from (2)
(2) {{{ 6b + 44a = 34000 }}}
(1) {{{ -6b - 10a = -17000 }}}
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{{{ 34a = 17000 }}}
{{{ a = 500 }}}
and
(1) {{{ 6b + 10a = 17000 }}}
(1) {{{ 3b + 5a = 8500 }}}
(1) {{{ 3b + 5*500 = 8500 }}}
(1) {{{ 3b = 8500 - 2500 }}}
(1) {{{ 3b = 6000 }}}
(1) {{{ b = 2000 }}}
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Each book costs 2000
Each pencil costs 500
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You can check by plugging these 
results back into (1) and (2)