Giải thích các bước giải:
a) -7.(5- x) - 2(x-10)=15
--> -35+7x -(2x-20)=15
--> -35+7x-2x+20=15
--> -15+5x=15
--> 5x= 30
--> x= 6
b)3.( x -4 ) - ( 8-x) = 12
-->3x-12-8+x=12
-->4x-20=12
-->4x=32
-->x=8
c)4.( x - 5 ) -3.(x+7) = -19
-->4x-20-(3x+21)= -19
-->4x-20-3x-21=-19
-->x-41=-19
-->x=22
d) 7. ( x - 3 ) -5.(3-x)= 11x - 9
-->7x-21- (15-5x)=11x-9
-->7x-21-15+5x-11x+9= 0
-->x-27=0
-->x=27
e) 4.( 2-x) +3. ( x-5)=14
-->8-4x+3x-15=14
-->-x-7=14
-->-x=21
-->x=-21
j) -5.(2-x)+4.( x-3 ) = 10x - 15
-->-10+5x+4x-12=10x-15
-->-22+9x-10x+15=0
-->-7-x=0
-->-x=7
-->x=-7
i)7.(x-9)-5.( 6 - x )= -6 + 11x
-->7x-63-(30-5x)=-6+11x
-->7x-63-30+5x=-6+11x
-->12x-93+6-11x=0
-->x-87=0
-->x=87
k) 5.(3-2x) +5.(x-4)=6-4x
-->15-10x+5x-20-6+4x=0
-->-11-x=0
-->-x=11
-->x=-11
