a, x = 2/25
b, x = 1/99
c,hình như đề sai
d, x = 1/4

a) x = 7/25 + -1/5
=> x = 7/25 - 5/25
=> x = 2/25
b) x = 5/11 + 4/-9
=> x = 5/11 - 4/9
=> x = 45/99 - 44/99
=> x = 1/99
c) 5/9 + x/-1 = -1/3
=> 5/9 - x = -1/3
=> x = 5/9 + 1/3
=> x = 5/9 + 3/9
=> x = 8/9
d) 3/4 - x = 1
=> x = 3/4 - 1
=> x = 3/4 - 4/4
=> x = -1/4

a) x = 7/25 + -1/5
x = 2/25
vạy x = 2/25
b) x = 5/11 + 4/-9
x = 1/99
vậy x = 1/99
c) 5/9 + x/-1 = -1/3
x/-1 = -8/9
x = 8/9
vậy x = 8/9
d) 3/4 - x = 1
x = -1/4
vậy x = -1/4