Question 801939
Let {{{ s }}} = Allison's speed rowing in still water
Let {{{ c }}} = the speed of the current
{{{ s - c }}} = her speed rowing against the current
{{{ s + c }}} = her speed rowing with the current
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Equation for rowing against the current:
(1) {{{ 1 = ( s - c )*(24/60) }}}
Equation for rowing with the current:
(2) {{{ 1 = ( s + c )*(13/60) }}}
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(1) {{{ 60 = 24s - 24c }}}
(1) {{{ 6s - 6c = 15 }}}
and
(2) {{{ 13s + 13c = 60 }}}
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Multiply both sides of (1) by {{{ 13/6 }}}
and add (1) and (2)
(2) {{{ 13s + 13c = 60 }}}
(1) {{{ 13s - 13c = 32.5 }}}
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{{{ 26s = 92.5 }}}
{{{ s = 3.558 }}} mi/hr
and, since
(1) {{{ 6s - 6c = 15 }}}
(1) {{{ 6*3.558 - 6c = 15 }}}
(1) {{{ 21.348 - 15 = 6c }}}
(1) {{{ 6c = 6.348 }}}
(1) {{{ c = 1.058 }}}
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Allison's speed rowing in still water is 3,558 mi/hr
The speed of the current is 1.058 mi/hr