Question 551951
Goofy had a head start of 
{{{ d[1] = 30*2 }}}
{{{ d[1] = 60 }}} mi
Start a stopwatch when Pluto leaves
Let {{{ d }}} = distance that Pluto travels until they meet
Let {{{ t }}} = time on stopwatch when Pluto
overtakes Goofy
Goofy's equation:
(1) {{{ d - 60 = 30t }}}
Pluto's equation:
(2) {{{ d = 45t }}}
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Substitute (2) into (1)
(1) {{{ 45t - 60 = 30t }}}
(1) {{{ 15t = 60 }}}
(1) {{{ t = 4 }}} hrs
Pluto overtook goofy in 4 hrs
check:
(2) {{{ d = 45t }}}
(2) {{{ d = 45*4 }}}
(2) {{{ d = 180 }}} mi
and
(1) {{{ d - 60 = 30t }}}
(1) {{{ d - 60 = 30*4 }}}
(1) {{{ d = 120 + 60 }}}
(1) {{{ d = 180 }}} mi
OK