Question 4285
You can eliminate the decimals by multiplying everything by 10.

10(0.5x + 3.4 = 0.2x + 12.4) = 5x + 34 = 2x + 124
Now subtract 2x from both sides.  3x + 34 = 124
Subtract 34 from both sides.            3x = 90
Divide both sides by 3.  x = 30

Check:
0.5(30) + 3.4 = 0.2(30) + 12.4
15 + 3.4 = 6 + 12.4
18.4 = 18.4   Solution is good.