Ok so I'm reviewing algebra since it was the only math class I didn't do well in and thought I would work out all the problems in the Schaum's Outline. I have ran across 3 problems I'm not sure how to do.

a)Two numbers have the ratio 3:4. If 4 is added to each of the numbers the resluting ratio is 4:5. Find the two numbers.

b) Determine whether the graph of each relation is symmetric with respect to the y axis, x axis, or origin.

I want to work this one out rather than look at the graph.

So it is symmetric with respect to the origin but is there a faster way of showing that. I tried going this route but got stuck

and then got stuck.

c)Find the largest rectangle which can be inscribed in a right triangle whose legs are 6 and 8 inches repectively.

I know

and

Thanks in advance