Question

TÌM x 

a) 120 - ( x- 135 ) = 300                            b) (102 - 3x ) :  3 = -19

Answer 1

\(a,120-\left(x-135\right)=300\)

\(x-135=120-300\)

\(x-135=-180\)

\(x=-180+135\)

\(x=-45\)

\(b,\left(102-3x\right):3=-19\)

\(102-3x=\left(-19\right)\times3\)

\(102-3x=57\)

\(3x=102-57\)

\(3x=45\)

\(x=15\)

Answer 2

a) 120 - ( x - 135 ) = 300

=> x - 135 = 120 - 300

=> x = ( -180 ) + 135

=> x = -45

b) ( 102 - 3x ) / 3 = -19

=> 102 - 3x = ( -19 ) * 3

=> 3x = 102 - ( -57 )

=> x = 159 / 3

=> x = 53