Question 847065
here's a solution with 2 variables:
Let {{{ s }}} = he speed of the bike
{{{ 4s }}} = the speed of the car
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Let {{{ d }}} = the distance in km the bike travels in 1 hour
{{{ d + 60 }}} = the distance the car travels in 1 hour
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Equation for the bike:
(1) {{{ d = s*1 }}}
Equation for the car:
(2) {{{ d + 60 = 4s*1 }}}
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Substitute (1) into (2)
(2) {{{ s + 60 = 4s*1 }}}
(2) {{{ 3s = 60 }}}
(2) {{{ s = 20 }}}
and
{{{ 4s = 80 }}}
The bike travels 20 km/hr
The car travels 80 km/hr
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check:
(1) {{{ d = s*1 }}}
(1) {{{ d = 20 }}} km
and
(2) {{{ d + 60 = 4s*1 }}}
(2) {{{ d + 60 = 4*20*1 }}}
(2) {{{ d = 80 - 60 }}}
(2) {{{ d = 20 }}} km
OK
Note that you can say {{{ y = d }}}
and {{{ x = s }}} in order to plot 
on x-y plane