Complementary angles add to 90 degrees. This means that 65 + x = 90, so x = 90 - 65 = 25.
The correct equation to solve for x would be 12x - 19 + 4x + 1 = 180
The answer is x equal 0 and y equal negative 3
Let x = the amount that Seini earned
Then x + 25 = the amount that Gavin
The amount Gavin earned would also = 425 - x (your directions asked you to have 2 equations.)
Together they earned 425:
x + (x + 25) = 425
2x + 25 = 425
2x = 400
Now divide both sides by 2 to find x.
Use all of this data to satisfy the directions.
I cannot suggest anything other than the set of real numbers here, but maybe someone else can provide a better answer. As long as you increase or decrease x (which is a real number) then you will get a real number, or the infinite set of real numbers.