Question

A. X + 18 + 8 x X = 99                             B. (7 +X) x 4 = 108                         C. (X + 15) : 3 = 3 x 8

Answer 1

a) x + 18 + 8 × x = 99

x + 8 × x = 99 - 18

x + 8 × x = 81

9 × x = 81

x = 81 ÷ 9 = 9

Vậy x = 9

b) ( 7 + x ) × 4 = 108

7 + x = 108 ÷ 4

7 + x = 27

x = 27 - 7 = 20

Vậy x = 20

c) ( x + 15 ) ÷ 3 = 3 × 8

( x + 15 ) ÷ 3 = 24

x + 15 = 24 × 3 = 72

x = 72 - 15 = 57

Vậy x = 57

Answer 2

A.X.1+18+8.X=99

=>X(1+8)+18  =99

=>X.9+18        =99

=>X9                =99-18

=>X9                 =81

=>X                   =81:9

=>X                   =9

B)(7+X).4=108

=>7+X     =108:4

=>7+X      =27

=>X          =27-7

=>X          =20

C)(x+15):3=3.8

=>(x+15):3=24

=>x+15      =24.3

=>x+15       =72

=>x              =72-15

=>x              =57