Question 729400
Let {{{ a }}} = hours worked after school
Let {{{ b }}} = hours worked on Saturday
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given:
(1) {{{ a + b = 12 }}}
(2) {{{ 4a + 5b = 52.5 }}}
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(2) {{{ 40a + 50b = 525 }}}
Multiply both sides of (1) by {{{ 40 }}}
and subtract (1) from (2)
(2) {{{ 40a + 50b = 525 }}}
(1) {{{ -40a - 40b = 480 }}}
{{{ 10b = 45 }}}
{{{ b = 4.5 }}}
and
(1) {{{ a + 4.5 = 12 }}}
(1) {{{ a = 7.5 }}}
He worked 7.5 hours worked after school
He worked 4.5 hours worked on Saturday
check:
(2) {{{ 4a + 5b = 52.5 }}}
(2) {{{ 4*7.5 + 5*4.5 = 52.5 }}}
(2) {{{ 30 + 22.5 = 52.5 }}}
(2) {{{ 52.5 = 52.5 }}}
OK