Absolute value inequality is given as
... (1)
Opening the absolute sign, we get
or

Combining the inequalities we get -

Add, A on both sides.

It is given that, C is between 77 gm and 85 gm
Hence ,
... (2)
.... (3)
solving equation (2) and (3)
A = 81 and B = 4
Plug the values of A and B in equation 1.
Absolute value equation is
