6
You've given the answer yourself. d=6 and f=3.
Assuming the sides of the triangle a=5, b=5 and c=6, the semiperimeter s=(5+5+6)/2=8. Height d=3 is not necessary if you use Heron´s formula for the area (A): A = [s(s-a)(s-b)(s-c)]1/2 = [8(8-5)(8-5)(8-6)]1/2 = [144]1/2 = 12
d = -6
D = 210
c = 6 and d = 7
6+6=12, easy :D
14
a7 = a1 + 6*D = 10 + 6*(-3) = 10 - 18 = -8
The d stands for distance.
30
A plus b plus c equals d. A is the largest answer b is the smallest answer and d is less than 6?''