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What is the answer to Q if  Q=a+bP
If P=a+b[(a-c)/(d-b)]
Please explain working out.

\(Q=a+b[a+b\frac{(a-c)}{(d-b)}]\\ Q=a+b[\frac{a(d-b)+b(a-c)}{(d-b)}]\\ Q=a+b[\frac{ad-ab+ba-bc}{(d-b)}]\\ Q=a+b[\frac{ad-bc}{(d-b)}]\\ Q=a+\frac{abd-b^2c}{(d-b)}\\ Q=\frac{ad-ab+abd-b^2c}{d-b}\\\)

That is it I think