25.
=99*[(1/99)-100]
=99*(1/99)-99*100
=1-9900
= - 9899
26.
= -4 -[3+(4/5)*(-5/2)+2]
= -4 -[3-2+2]
= -4-3
= - 7
27.
3x-2x=6+1
x=7
28.
-4x+(5/2)x=8+1
-(3/2)x=9
x= -9*(2/3)
x= - 6
29.
5x+2x=(1/2)-1-1
7x= - 3/2
x= - 3/14
30.
-4x+(5/2)x=8+1
-(3/2)x=9
x= - 9*(2/3)
x= - 6