Question 433242
Let {{{s}}} = a side of the square fountain
The walk adds {{{2*3.5 = 7}}} ft to the width
given:
{{{ (s + 7)^2 =  700 }}}
Take the square root of both sides
{{{ s + 7 = 10*sqrt(7) }}}
{{{ s = 26.457 - 7 }}}
{{{ s = 19.457 }}}
The fountain measures 19.457 x 19.457 ft2