Question 111323
w = weeks from now
{{{5w + 60}}} is the amount of money I'll have in {{{w}}} weeks
{{{135 - 10w}}} is the amount of money my sister will have  in {{{w}}} weeks
These amounts will be equal when {{{5w + 60 = 135 - 10w}}}
{{{15w = 75}}}
{{{w = 5}}}
So, in 5 weeks we'll have the same amount
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check answer
{{{5w + 60 = 135 - 10w}}}
{{{5*5 + 60 = 135 - 10*5}}}
{{{25 + 60 = 135 - 50}}}
{{{85 = 85}}}
OK