The experienced worker works at twice the speed of the apprentice so let's call his part of any given job 2x and call the Apprentice's part of the job x.
When the work together they are ADDING there efforts so, if a job takes 3 hours than, it can be expressed as:
...

Sorry but this does not make much sense. There are two equals signs in your denominators. I know that it is very difficult to input math information with this editor, but please check your symbols, and submit with question again. Thank you.

I think Vivian has done an excellent job here, and I agree with her assessment of problem 3. The way it is written, it is unsolvable with out more information. However, maybe there was a typo, and it should read: "He plans to read 20 PAGES tomorrow on his crumpet break." If this...

To make it dead simple, a rational expression is just a fraction with some variables shoved in there, either on top or on the bottom, but usually both. It really is that simple to understand what they are, but working with rational expressions can be quite complicated.

For #1:
To be precise, this is not a polynomial. Polynomial have monomials added together arranged in descending degrees for their variables. This is called a rational expression. What you should do to simplify it, is to just cancel the powers of similar variables on the top and bottom...

Sorry Benjamin,
You do have a problem at step 3. 5/3(d) = 1 * 3 does not lead to 5d = 3.
It leads to 5 / d = 3.
Cancelling the 3 on the bottom does not bring the d to the top of the fraction.
Next you would multiply both sides by 1/5.
(1/5) 5 / d = 3 (1/5) which...

Jusin I.'s answer is correct. I would just suggest using the letters a (for adult) and c (for children) as the variable names. These will be a better reminder of what the variables mean. Here is the check that he recommends using these letters.
4s + 2c = 80 Check...

I like Uzair Q's answer the best, but lets give a more general answer and use the correct vocabulary. The equation we are considering is a faction multiplied by a variable on the left side. To clear this faction and get the variable by itself, we multiply by the reciprocal fraction. This is the...

Solving an inequality is largely the same as solving an equation. The graphing is also quite similar.
The one, important rule change is that if you divide or multiply by a negative number you should flip the inequality sign to the other direction. For example:
-14x > 56 Divide both...