Question 478379
Let {{{s}}} = Jody's speed
Let {{{t}}} = the time elapsed until
they are 45 mi apart
Maria's equation:
(1) {{{ d = ( s + 30 )*t }}}
Jody's equation:
(2) {{{ d - 45 = s*t }}}
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Substitute (2) into (1)
(1) {{{ d = s*t  + 30t }}}
(1) {{{ d = d - 45 + 30t }}}
Subtract {{{d}}} from both sides
(1) {{{ 45 = 30t }}}
(1) {{{ t = 1.5 }}}
It will take 1.5 hrs
check answer:
(1) {{{ d = (s + 30)*t }}}
(1) {{{ d = 1.5s + 45 }}}
and
(2) {{{ 1.5s + 45  - 45 = 1.5s }}}
OK