Question 1165697
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<pre>

Let "d" be the lake's width.


Then you have this "time" equation


    {{{d/10}}} + {{{d/8}}} = 1   hour.


Multiply both sides by 40


    4d + 5d = 40

    9d      = 40

     d      = 40/9 = 4 {{{4/9}}}  miles.     <U>ANSWER</U>
</pre>

Solved.