120x4+120x6

=120x[4+6]

=120x10

=1200

15 + 15 = 30 bạn nhé

=30

k mk nha!!!

=30

ai k mình mình k cho

50+40=90

a, - ( x + 84 ) + 213 = -16

=> - ( x + 84 ) = -16 - 213

=>  - ( x + 84 ) =-229

=> x + 84 = 229

=> x = 145

b.  x + ( -35 ) = 18

=> x = 18 - ( -35 )

=> x = 18 + 35

=> x = 53

c. -2x - ( - 17 ) = 15

=> -2x = 15 + ( -17)

=> -2x = -2 

=> x = 1

x = 30 - 10

x = 20