maths

1. c=5(a-1)(b-1)/2
c= 2.5(ab-a-b+1)
= 2.5ab-2.5a-2.5b+2.5 ,,

2. e=10(a+b)-2(c-d)
=10a+10b-2c+2d ,,

3.f=e(45-d)(c-10)
=e(45c-450-cd+10d)
=45ce-450e-cde+10de ,,

4.g=(9f/9000)(f/9000)-(e-3d+c-3b-3a)
=9f^2/81000-e+3d-c+3b+3a
=f^2/9000-e+3d-c+3b+3a