Question 1112435
Let {{{ a }}} = the cost of 1 marker in cents
Let {{{ b }}} = the cost of 1 pen in cents
-----------------------------------
(1) {{{ 4a + 5b = 671 }}}
(2) {{{ 5a + 3b = 712 }}}
-------------------------
Multiply both sides of (1) by {{{ 3 }}}
Multiply both sides of (2) by {{{ 5 }}}
and subtract (1) from (2)
-----------------------------------
(2) {{{ 25a + 15b = 3560 }}}
(1) {{{ -12a - 15b = -2013 }}}
------------------------------
{{{ 13a = 1547 }}}
{{{ a = 119 }}}
and
(1) {{{ 4a + 5b = 671 }}}
(1) {{{ 4*119 + 5b = 671 }}}
(1) {{{ 476 + 5b = 671 }}}
(1) {{{ 5b = 195 }}}
(1) {{{ b = 39 }}}
-----------------------------
One marker costs $1.19
One pen costs $.39
-----------------------------
check answers:
(2) {{{ 5a + 3b = 712 }}}
(2) {{{ 5*119 + 3*39 = 712 }}}
(2) {{{ 595 + 117 = 712 }}}
(2) {{{ 712 = 712 }}}
OK