Solve the following pair of linear equations:
(i) `p x+q y=p q ;\ q x p y=p+q`
(ii) `a x+b y=c ;\ b x+a y=1+c`
(iii) `x/a-y/b=0`; `a x+b y=a^2+b^2`
(iv) `(a-b)x+(a+b)y=a^2-2a b-b^2;``(a+b)(x+y)=a^2+b^2`
(v) 152x − 378y = − 74; 76x − 189y = − 37

Explanation

To solve the given pairs of linear equations step by step, we will use different methods such as substitution, elimination, and cross-multiplication as appropriate.

### (i) Solve the equations:
1. **Equations:**
\[ px + qy = pq \quad \text{(1)} \]
\[
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