Tìm x: 2x-15=x+8

1.Tìm x:
a,2x-15=x+8
b,15+14+13+...+x=15
c,|x+4|+|2-x|=0
d,( x+1)(x - 2) = 0
e,(b+1)( b-4) < 0
f,(b+4)( b +7) < 0
g,(b+5)(b-2) > 0
h,(b-1)( (b-10) < 0
i,(b+1)( (b- 5) < 0