Answer:
x = 15/(3y + 1)
Explanation:
There's an operator missing between 3x and 9y, but let's do it both ways for practice.
If it was supposed to be a minus sign, then:
3x - 9xy = 15
That x in the second term complicates things, but first let's simplify this equation by dividing both sides by 3. We get:
x + 3xy = 5
It's the same equality, right? If you put an (x,y) in both equations you'd get the same answer. This is just cleaner to work with.
We need x all by itself, so a way to do that is to factor x our of (x + 3xy) to get:
x(1+3y) Or in more-common form: x(3y + 1).
Since x was in both terms I get to bring it to the outside of the parentheses. With more practice that will be easier to see. If you multiply that expression back out you'll see you get back to what it was before:
x(3y + 1) = 3xy + x Which is the same thing as x + 3xy, right? Just turned around.
So now the equation looks like this and we can solve for x:
x(3y +1) = 15
So x = 15/(3y + 1)
If the missing sign was supposed to be a plus sign I'll leave it to you to work out. It'll look almost the same, but the 3y term will be negative.