a) 1/3 + x =-1/4
x = -1/4 -1/3 = -7/12
b) -2/15 - x = -3/10 
x = -2/15 + 3/10 =1/6
c) 2/3 - 1 4/15x =-3/5
2/3 - 19/15x = -3/5
19/15x = 2/3 + 3/5 = 19/15
=> x = 1
d) 11/12 - (2/5 - x) = 2/3
2/5 - x = 11/12 - 2/3 = 1/4
x =2/5 - 1/4 = 3/20
e) 2x(x-2/3) = 0
=> x = 0 hoặc x -2/3=0
=> x =0 hoặc x=2/3
f) 2^(x-1)= 16
2^(x-1)= 2^4
=> x-1=4
=>x=5
g) căn của x+1 = 5
=> x+ 1 = 5^2 = 25
=> x = 24
h) |x-3/4| - 1/2 = -1/5
|x-3/4|= -1/5 + 1/2 = 3/10
=> x-3/4 =3/10 hoặc x -3/4 = -3/10
=> x = 21/20 hoặc x = 9/20
i) (x-1/3)^3 = -8/27 = (-2/3)^3
=> x- 1/3 = -2/3
=> x= -2/3+ 1/3 = -1/3
k) (-1/3)^(2x-1)= -1/27
(-1/3)^(2x-1)= (-1/3)^3
=> 2x-1=3
=> 2x=4
=> x=2
l) x/-18 =-8/12
=> 12x = 8 . 18 =144
=> x = 12
m) (7+x)/(x-13)= 3/7
=> 7(7+x)= 3(x-13)
49 + 7x = 3x- 39
7x - 3x = -39 - 49
4x = -88
=> x =-22