bài 10
a.x -5=-1
x = -1+5
x =4
b, - 30 + ( 25 – x) = - 1
-30 +25-x=-1
-5-x=-1
x=-5-(-1)
x= -4
c, x-(-24) = 3
x +24=3
x =24+3
x = 27
d) ( x – 29 ) – ( 17 – 38 ) = - 9
x-29-17+38=-9
x-18=-9
x =9
e, 22 – ( - x ) = 12
22+x=12
x=12-22
x=-10
f,(x + 5 ) + (x-9)=x+2
x+5 +x-9=x+2
2x-4=x+2
2x-4-x-2=0
x-6=0
x =6
g,( 27- x) + ( 15 + x ) = x – 24
27-x+15+x=x-24
42=x-24
-x=-24-42
-x=-66
x=66
bài 11
a, -37+54+(-70)+(-163)+246
= (-137-163)+(54+246)+(-70)
= -300+300+(-70)
=-70
b) -359+181+(-123)+350+(-17)
= (-359+350)+(-123+-17)+181
= 9+(-140)+181
=(9+181)+(-140)
=190+(-140)
=50
c) -69+53+46+(-94)+(-14)+78
=(-94+-14)-69+53+46+78
=-108-69+53+46+78
=(-108+78)+[(53+46)-69]
=-30+30
=0