Question 850421
4 times as fast means A can paint 
4 times as many rooms/week as B
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Let {{{ n }}} = number of rooms/wk
that B can paint
Add their rates of working to get 
their rate working together
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( 60 rooms ) / ( 1 wk ) = their rate working together
( 4n rooms ) / ( 1 wk ) = A's rate of working
( n rooms ) / ( 1 wk ) = B's rate of working
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{{{ (4n) / 1 + n / 1  = 60 / 1 }}}
{{{ 5n = 60 }}}
{{{ n = 12 }}}
{{{ 4n = 48 }}}
A can paint 48 rooms in 1 week
check:
{{{ (4n) / 1 + n / 1  = 60 / 1 }}}
{{{ 48 / 1 + 12 / 1  = 60 / 1 }}}
{{{ 60 = 60 }}}
OK