1. Immediately I see that I can cancel equation 2 by a factor of 5:

If I multiply this equation by 2 I get equation 1 which would lead to the problem you're getting. It means there are infinite solutions

2. note that and

Let and it reduces to which should be easier to factorise

3. Find out where x=0 and where y=0. For where x=0 solve f(0) and this will usually be the lowest point. To find where y=0 set f(x) to 0 and solve. This will give the x-intercepts.

Using these three points sketch the graph