Respuesta :

If you have a graphing calculator one way to know you are right is put the left side in Y1 and the right side in Y2 then hit 2nd trace and intersection then find the intersection and the X value is your answer. If you don't have a graphing calculator then I'm sorry
0.4(5+2x)-0.5=3(0.3x+0.7)
2+0.8x-0.5=0.9x+2.1
0.8x-0.9x=2.1-2+0.5
-0.1x=2.5
x=-25