Question

essa e a ultima que falta para responder .

Answer 1

2x+3x+4x=189
5x+4x=189
9x=189
x=189/9
x=21

8x-9-x=-1
     5
8x-9-x=-1·5
8x-9-x=-5
8x-x=-5+9
7x=4
x=4/7