Question 500835
Add their rates of working
given:
sally's rate:
{{{ 1/8 }}} = 1 room in 8 hours
Steve's rate:
{{{ 1/9 }}}  = 1 room in 9 hours
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{{{ 1/8 + 1/9 = 1/x }}}
{{{ 9/72 + 8/72 = 1/x }}}
{{{ 9x + 8x = 72 }}}
{{{ 17x = 72 }}}
{{{ x = 4.235 }}}
{{{ .235*60 = 14.118 }}}
{{{ .118*60  = 7 }}}
4 hours 14 min 7 sec