Which expression represents 2 times the sum of 5 and 7?

Which formula gives the area of a triangle? a=1/2(b+h)

The expression 42 plus 57 shows how much money nate spent at a store .which expression also shows how much money nate spend

The length of a rectangular board is 3 feet less than twice its width. a second rectangular board is such that each of its dimensions is the reciprocal of the corresponding dimensions of the first rectangular board. if the perimeter of the second board is one-fifth the perimeter of the first, what is the perimeter of the first rectangular board?