In Triangle PQR, A, B and C are midpoints of PQ, QR and RP respectively. If AB:BC:CA=3:4:5 and QR=20, find perimeter of triangle PQR. I want in full explanation and method.
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Convert 16 yards to feet use the conversion rate 3 feet = 1 yard

Evaluate the expression for the given value of the variable. | ? 4 b ? 8 | + ? ? ? 1 ? b 2 ? ? + 2 b 3 -4b-8+-1-b2+2b3 ; b = ? 2 b=-2

Afarmer has a large field that is x feet in length. he wants to fence in a rectangular section in the middle of the field , leaving a length of 100 feet of open field behind each end of the fenced rectangle.he also wants the width of the fenced-in space to be 100 feet less than its length. find the expressions to represent the length and width of the fenced section of the field