Question 1050412
Let {{{ c }}} = the speed of the current
Let {{{ s }}} = the speed of the boat in still water
(1) {{{ s + c = 13 }}}
(2) {{{ s - c = 3 }}}
Add the equations:
{{{ 2s = 16 }}}
{{{ s = 8 }}}
and
(1) {{{ 8 + c = 13 }}}
(1) {{{ c = 5 }}}
The speed of the current is 5 km/hr
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check answer:
(2) {{{ s - c = 3 }}}
(2) {{{ 8 - c = 3 }}}
(2) {{{ c = 5 }}}
OK
You can get a 2nd opinion if you want