Question 1140362
Jan's rate of working is
[ 1 floor sanded ] / [ 6 hrs ] = {{{ 1/6 }}}
Let {{{ t }}} = Thumelo's time working alone
{{{ 1/( (5/8)*6 ) = 4/15 }}}
Add their rates of working to get their rate working together
{{{ 1/6 + 1/t = 4/15 }}}
Multiply both sides by {{{ 90t }}}
{{{ 15t + 90 = 24t }}}
{{{ 9t = 90 }}}
{{{ t = 10 }}}
It takes him 10 hrs working alone
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check:
{{{ 1/6 + 1/10 = 4/15 }}}
Multiply both sides by {{{ 30 }}}
{{{ 5 + 3 = 8 }}}
{{{ 8 = 8 }}}
OK