Please help 1) 18 9/11+8 11/14+21211+15 3/14
2)1/2 + 2 3/4
3)What is the perimeter of this figure?

Simplify 5 square root of 7 end root plus 12 square root of 6 end root minus 10 square root of 7 end root minus 5 square root of 6 . (1 point) 5 square root of 14 end root minus 7 square root of 12 5 square root of 7 end root minus 7 square root of 6 7 square root of 12 end root minus 5 square root of 14 7 square root of 6 end root minus 5 square root of 7

How many triangles can be drawn with side lengths 4 centimeters, 4.5 centimeters, and 9 centimeters? explain

Ibeg you to me 20. a reaction produces 4.93 l of oxygen, but was supposed to produce 1 mol of oxygen. what is the percent yield?