the sides of a triangle are in the ratio 5 : 12 : 13 and its perimeter is 420 m , its area is ?
"5 x + 12 x + 13 x = 420 = > x = 14 a = 70 , b = 168 , c = 182 s = ( 70 + 168 + 182 ) / 2 = 210 answer : d"
multiply(420, divide(420, add(add(5, 12), 13)))