First, rewrite the equation as:
P_(SELL) = (26.65 * 26.65 * 17 * P_(SELL))/1.57 ->
P_(SELL) = (12073.7825 * P_(SELL))/1.57
P_(SELL) = 7690.31 * P_(SELL)
Subtract color(red)(P_(SELL)) from each side of the equation:
P_(SELL) - color(red)(P_(SELL)) = 7690.31 * P_(SELL) - color(red)(P_(SELL))
0 = (7690.31 - 1)color(red)(P_(SELL))
0 = 7689.31 * color(red)(P_(SELL))
Now, divide each side of the equation by color(red)(7689.31) to solve for P_(SELL):
0/color(red)(7689.31) = (7689.31 * P_(SELL))/color(red)(7689.31)
0 = (color(red)(cancel(color(black)(7689.31))) * P_(SELL))/cancel(color(red)(7689.31))
0 = P_(SELL)
P_(SELL) = 0