Question 1200591
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If p=6q-r and t=3q+r , find p in terms of r and t .
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<pre>
We should exclude q from p=6q-r, using the second equation t=3q+r.


    So, from t=3q+r we find  q= {{{(t-r)/3}}}  and then substitute it into
    the first equation, replacing q there.  We get then

        p = {{{6*((t-r)/3) - r}}} = 2*(t-r) - r = 2t - 2r - r = 2t - 3r,


    exactly as your answer says.
</pre>

Solved, with complete explanations.