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The perimeter of a stage is 116 feet. it is 17 feet wide. how long is it?

For the rule of 78, for a 12-month period, the last term in the sequence is 12 and the series sums to 78. for an 10 month period, the last term is and the series sum is . for a 15 month period, the last term is and the series sum is . for a 20 month period, the last term is and the series sum is

What is 10+10+20 about the origin the square root of a triangle.