In getting the area of and equilateral triangle, you must first consider that all of its sides are congruent and that is 3 inches, so the formula in getting the area is height form its base so in getting its height you must use the pythagorean theorem by dividing the triangle so the hypotenuse of it is 3 and the base of 1.5inches, so the height is 4.77 inches then the area is 7.15 sqr.inch
It is equal because every 2000 pounds is 1 ton and 18000lb divided by 2000 equals 9.