Simple calculation of 37 × (1 / 80 + 1 / 43) - 43 × (1 / 37-1 / 80) + 80 × (1 / 37-1 / 43)

Simple calculation of 37 × (1 / 80 + 1 / 43) - 43 × (1 / 37-1 / 80) + 80 × (1 / 37-1 / 43)

=37/80+37/43-43/37+43/80+80/37-80/43
=(37/80+47/80)+(37/43-80/43)+(-43/37+80/37)
=1+(-1)+1
=1