(p / 649.98) x 100 = 215.6 i need to find what p equals

As with any linear equation of this sort, multiply by the inverse of the coefficient of p.
  p = 215.6*(649.98/100)
  p = 1401.35688


The above value for p will reproduce your result exactly. In some contexts, you would be asked to round it to 4 significant figures, 1401, to match the precision of the number 215.6.