Question 1043784
I just have to end up with {{{ j = f(s) }}}
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Let {{{ j }}} = John's present age
Let {{{ s }}} = Sharon's present age
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(1) {{{ s + j = 70 }}}
(2) {{{ j = 4s }}}
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(1) {{{ j = -s + 70 }}}
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Substitute (2) into (1)
(1) {{{ s + 4s = 70 }}}
(1) {{{ 5s = 70 }}}
(1) {{{ s = 14 }}}
and
(2) {{{ j = 4s }}}
(2) {{{ j = 4*14 }}}
(2) {{{ j = 56 }}}
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The solution is ( 14,56 )
The system of equations is:
(1) {{{ j = -s + 70 }}}
(2) {{{ j = 4s }}}
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Here is the plot:
{{{ graph( 400, 400, -10, 100, -10, 100, -x + 70, 4x ) }}}