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Find the value of x for which line a is parallel to line b

The sum of the first eight terms of an arithmetic progression is 9m + 14. the fifth term of the06 progression is 2m - 6, where m is a constant.given that the first term of the progression is 26,find the value of the common difference, d and thevalue of m.

Alex measured the length of an item to be 3.7 cm. the actual length is 3.5 cm. what is alex’s percent error?