# Math Help - Determine values

1. ## Determine values

Dear all,

Would appreciate some guidance for this question:

If q = ax + by and r = bx - ay, determine the value of:

Thank you.

2. If $q=ax+by$ then would $\frac{dq}{dx}=a$ so $\frac{dq}{dx}\frac{1}{y}=\frac{1}{y}$?

Is b also a constant?

3. Had edited the equation above in image format for better viewing.
Thank you...