I would say the answer would be 105
<em>x</em>/<em>r</em> + <em>x</em>/<em>w</em> + <em>x</em>/<em>t</em> = 1
<em>x</em> (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>) = 1
<em>x</em> = 1 / (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>)
To make the solution a bit cleaner, multiply through the numerator and denominator by the LCM of each fraction's denominator, <em>rwt</em> :
<em>x</em> = 1 / (1/<em>r</em> + 1/<em>w</em> + 1/<em>t</em>) • <em>rwt</em> / <em>rwt</em>
<em>x</em> = <em>rwt</em> / (<em>rwt</em>/<em>r</em> + <em>rwt</em>/<em>w</em> + <em>rwt</em>/<em>t</em>)
<em>x</em> = <em>rwt</em> / (<em>wt</em> + <em>rt</em> + <em>rw</em>)
The equation of the circle is written as: (x - h)² + (y - k)² = r²
(h,k) are the points of the center of the circle.
r is the radius.
In case of the given equation the center is (-3,-5)
Hope this helps :)
If you divide a number by 9 then you can also divide it by 3.