Question 334085
if they are to meet, the presumption (since not stated) is that they are walking toward each other.
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let {{{d[A]}}}=distance walked by A
let {{{d[B]}}}=distance walked by B
let {{{r[A]}}}=walking rate by A = 80 kmph
let {{{r[B]}}}=walking rate by B = 60 kmph
let t=time they meet
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you need to know the relationship:   distance = rate*time: d=r*t
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given d={{{d[A]+d[B]=210 km}}}
d={{{r[A]*t+r[B]*t }}}  (same t because they meet at a common time)
210=80*t+60*t=140*t
210/140=t
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t=1.5 hours