1.Tìm x, biết a, 11/13 – ( 5/42 – x ) = – (15/28 – 11/13 ) b, x + 1/3 = 2/5 – ( -1/3) c, – 5/8 – x = – 3/20 – (-1/6) d, x – (-1/4) = -5/6+1/8 e,

a, 11/13 – (5/42 – x) = – (15/28 – 11/13)

→              5/42-x     = 113/364+11/13

→                       x     = 5/42-421/364

→                       x     = -1133/1092

b, x + 1/3 = 2/5 – ( -1/3)

→ x           = 11/15-1/3

→ x           = 2/5

c, – 5/8 – x = – 3/20 – (-1/6)

→ x            = -5/8-1/60

→ x            = -77/120

d, x – (-1/4) = -5/6+1/8

→ x              = -17/24+(-1/4)

→ x              = -23/4

e, -2/3 x = 4/15

→         x = 4/15:(-2/3)

→         x = -2/5

g, x : 22/15 = -8/27

→ x             = -8/27.22/15

→ x             = -176/405