Question 978347
Let {{{ t }}} = time in hrs when the
boats will be {{{ 33 }}} mi apart
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Let {{{ d }}} = distance in miles that the
slower boat travels in time {{{ t }}}
{{{ 33 - d }}} = distance the faster 
boat travels in time {{{ t }}}
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Equation for the slower boat:
(1) {{{ d = 10t }}}
Eqation for the faster boat:
(2) {{{ 33 - d = 12t }}}
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Substitute (1) into (2)
(2) {{{ 33 - 10t = 12t }}}
(2) {{{ 22t = 33 }}}
(2) {{{ t = 3/2 }}}
The boats will be 33 mi apart in 1 hr 30 min
check:
(1) {{{ d = 10*(3/2) }}}
(1) {{{ d = 15 }}}
and
(2) {{{ 33 - d = 12*(3/2) }}}
(2) {{{ d = 33 - 18 }}}
(2) {{{ d = 15 }}}
OK