Question 623239
Let {{{ s }}} = the speed of the bicycle club members
How much of a head start did the bicycle club members have?
{{{ d[1] = s*1.5 }}} km
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Start a stop watch when Manu leaves
Both he and the b.c.m. will travel for the same length of time 
on the stop watch.
b.c.m. equation:
(1) {{{ 24 - 1.5s = s*t }}}
Manu's equation:
(2) {{{ 24 = 4s*t }}}
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(2) {{{ t = 6/s }}}
Substitute this into (1)
(1) {{{ 24 - 1.5s = s*(6/s) }}}
(1) {{{ 24 - 1.5s = 6 }}}
(1) {{{ 1.5s = 24 - 6 }}}
(1) {{{ 1.5s = 18 }}}
(1) {{{ s = 12 }}}
{{{ 4s = 48 }}} 
Manu.s speed is 48 km/hr
check:
(2) {{{ 24 = 4s*t }}}
(2) {{{ 48t = 24 }}}
(2) {{{ t = .5 }}} hrs
and
(1) {{{ 24 - 1.5s = s*.5 }}}
(1) {{{ .5s + 1.5s = 24 }}}
(1) {{{ 2s = 24 }}}
(1) {{{ s = 12 }}}
OK