Question 209790
Write an equation for each one
{{{d[b] = r[b]*t[b]}}}
and
{{{d[s] = r[s]*t[s]}}}
given:
{{{d[b] = 600}}} mi
{{{d[s] = 500}}} mi
{{{t[b] = t[s]}}} hr (call them both {{{t}}})
{{{r[b] = r[s] + 10}}} mi/hr
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Rewrite equations:
{{{d[b] = r[b]*t[b]}}}
{{{600 = (r[s] + 10)*t}}}
{{{600 = r[s]*t + 10t}}}
and
{{{d[s] = r[s]*t[s]}}}
{{{500 = r[s]*t}}}
By substitution:
{{{600 = 500 + 10t}}}
{{{10t = 100}}}
{{{t = 10}}} hrs
and
{{{600 = r[b]*t}}}
{{{600 = r[b]*10}}}
{{{r[b] = 60}}} mi/hr
and
{{{500 = r[s]*t}}}
{{{500 = r[s]*10}}}
{{{r[s] = 50}}} mi/hr
Bev drives 60 mi/hr
check:
{{{d[b] = r[b]*t[b]}}}
{{{600 = 60*10}}}
{{{600 = 600}}}
and
{{{d[s] = r[s]*t[s]}}}
{{{500 = 50*10}}}
{{{500 = 500}}}
OK