Consider the variation of Gauss-Jordan elimination in which zeros are introduced above and below a leading 1

Question:

Consider the variation of Gauss-Jordan elimination in which zeros are introduced above and below a leading 1 as soon as it is obtained, and let A be an invertible n × n matrix. Show that to solve a linear system Ax = b using this version of Gauss-Jordan elimination requires
n3/2 + n2/2 multiplications and n3/2 - n/2 additions