<PRE><B>Question 1108308</B>
Parallel lines have the same slope
the slope is difference in y divided by difference in x.  For the first pair, it is
5/(1-a) = (-7)/(a+2+7), which is (a+9)
Cross-multiply
(-7)(1-a)=5(a+9)
-7+7a=5a+45
2a=52
a=26  ANSWER
(26, 1) and (1, 6) which has a slope of 5/-25 or -1/5
(-7, 8) and (28, 1) which has a slope of -7/25 or -1/5
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