Question 1122487
Let {{{ s }}} = Ndiba’s average speed
{{{ s*2 }}} = distance Ndiba travels before Emily leaves
Let {{{ d }}} = distance Emily travels until they meet
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Neiba’s equation:
(1) {{{ d - 2s = s*3 }}}
Emily’s equation:
(2) {{{ d = 70*3 }}}
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(1) {{{ d = 5s }}}
And
(2) {{{ 5s = 70*3 }}}
(2) {{{ s = 42 }}}
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Ndiba’s average speed is 42 km/hr
Check:
In 1st 2 hrs N traveled {{{ s*2 = 84 }}} km
In next 3 hrs she traveled {{{ s*1 = 126 }}} km
{{{ 84 + 126 = 210 }}} which was Emily’s distance
Since {{{ d = 70*3 }}}
Get 2nd opinion if needed