Question 1200591
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The given information shows p and t in terms of q and r, and it asks for p in terms of r and t.  That means you need to eliminate q.<br>
You eliminated p to get p in terms of q and t.  You did that correctly -- but it was not what the question asked for.<br>
The given equations are
p = 6q - r
t = 3q + r<br>
By standard algebraic processes, to eliminate q you could solve one of the equations for q and substitute in the other equation.<br>
But seeing that one equation has "6q" and the other has "3q", you can do the elimination more easily.<br>
Multiply the second equation by 2 so that both equations have "6q":<br>
p = 6q - r
2t = 6q + 2r<br>
Now solve one of the equations for "6q" and substitute the expression for 6q in the other equation.<br>
6q = p + r
2t = (p+r)+2r = p + 3r<br>
And then solve for p<br>
2t = p + 3r
p = 2t-3r<br>