Question

please explain to me how 3.2÷4=0.8 is done

Answer 1

To make it easier just assume there is no decimal point then just work out the 32÷4 where we know that 4 goes into 32 8 times so you get 8 remember the decimal point and since it was one decimal place you will push the decimal over to the left of 8 and that is how you get 0.8

Answer 2

So the idea with literal equations is to get one variable in terms of all the rest.  In this equation, we are trying to solve for x in terms of y (meaning that we are trying to get x all by itself with y on the other side of the equal sign).  Whenever you have a single fraction by itself on one side of an equal sign, the first thing that I always do is cross multiply.  This gets rid of the fraction completely and makes everything look a little nicer:

y * (5-4x) = 1 * (2x+3)

Distribute on the left side:

5y-4xy = 2x+3

Move the x's all to the same side.  I'm doing this by subtracting 2x from both sides:

5y-4xy - 2x = 3

For simplicity's sake, move 5y to the right side of the equation by subtracting it from both sides:

-4xy - 2x = 3 - 5y

Factor out the x on the left side:

x (-4y-2) = 3 - 5y

Get the x term by itself on the left side by dividing both sides by -4y-2.

x = (3-5y)/(-4y-2)

 

And there you have it!  I hope that this helped a little.  Good luck!