Question 759959
Let {{{ t[1] }}} = time when driving at 60 mi/hr
Let {{{ t[2] }}} = time when driving at 55 mi/hr
Driving at 60 mi/hr:
{{{ 18 = 60t[1] }}}
{{{ t[1] = .3 }}}
Driving at 55 mi/hr:
{{{ 18 = 55t[2] }}}
{{{ t[2] = .3273 }}}
{{{ t[2] - t[1] = .3273 - .3 }}}
{{{ t[2] - t[1] = .0273 }}}
{{{ .0273*60 = 1.636 }}}
{{{ .636*60 = 38 }}}
By driving 18 mi at 60 instead of 55, you save
1 min 38 sec