Please help using 30-60-90 ( Special Right Triangle)

Table which ratio is equivalent to 3: 7? 6: 7 3: 21 24: 56 15: 30

The perimeter of a rectangular lot of land is 436 ft. this includes an easement of x feet of uniform width inside the lot on which no building can be done. if the buildable area is 122 ft by 60 ft, determine the width of the easement. select one: a. 9 feet b. 18 feet c. 4.5 feet d. 7 feet

What is the value of n in the equation -1/2(2n+4)+6=-9+4(2n+1)