Question 608476
A model that best describes the writing test scores (w) for boys is w=-x+140. For girls a good model is w=1/4x+159. In both models x is the number of years after 1998. Assuming these models to be valid for the coming years, when will the average scores for girls be 49 points higher than for boys. 
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Solve:
girls ave - boys ave = 49
(1/4)x+159 - (-x+140) = 49
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(1/4)x + 159 +x - 140 = 49
(5/4)x = -110
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Comment: Something is wrong with the data you posted.
The answer is -88, which is probably wrong.
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Cheers,
Stan H.