Converting decimals to fractions:
Just put the decimal over the appropriate power of ten and simplify.
For example, with (five tenths) put 5 over 10, like so: . Now we can simplify to .
For (twenty-five hundredths), put 25 over 100: . Now simplify to .
If you have a larger number, like (one and seven tenths), use the same process, making an improper fraction (a larger number on top than on bottom). Put 17 over 10: . This one can't be simplified further.
Converting fractions to decimals:
The first way to do this needs a power of ten in the denominator (bottom) of the fraction. With this method, just reverse the above process and put the number in the numerator (top) of the fraction to the right of the decimal.
For "7 over 10" or (seven tenths):
For "29 over 100" or (twenty-nine hundredths):
The other way is to, with a calculator or on paper, divide the first number (numerator) by the second (denominator).
With "3 over 6" or , do 3 divided by 6 to get your answer (in this case, ).
As for the equations on the top, find an Algebra 1/Elementary Algebra/Beginning Algebra book and start working through it.
If you haven't done anything at all with linear equations before, then there are quite a few things you need to learn before you can start to solve equations like that.