First, you should think of things in fractions. 0.20.2 is a nasty way to think about the 1/515 because fractions were made to make things like multiplication easier. So let's rewrite this:
(1/5x +3)(4x -3/10)(15x+3)(4x−310)
From here, you can cross multiply. This means that we will be taking 1/5x15x and multiplying it across to the other parentheses containing (4x - 3/10)(4x−310). We will do the same with our +3+3 in the first parentheses. After that is done, we've finished.
So, first things first, 1/5x xx 4x15x×4x which is 4/5x^245x2 as the 4 moves on top and get's divided by 5, and the variable, xx, gets doubles making x^2x2. Then, 1/5x xx -3/1015x×−310 which gives us -3/50x−350x because the fractions simply multiply across, 1xx31×3 and 2xx102×10. Then all you have left to do is the same with the 3.
You will find that the answer is
4/5x^2 -3/50x + 12x - 9/1045x2−350x+12x−910
From here, we just want to simply our like terms, meaning the single x's. Then you'll have:
4/5x^2 + 597/600x -9/1045x2+597600x−910
We can express this in a different way. Since the original question used decimals, we can write the answer as:
0.8x^2 + 0.995x -0.90.8x2+0.995x−0.9
