D stands for 500 (Quingenti) and before you say but 'D' isn't the first letter of Quingenti, V is not the first letter of Quinque (5) and X is not the first letter of Decem (10).
d=3c
The answer might depend on what c and d are supposed to be!
c = 6 and d = 7
If a=b and c=d then (a+c)=(b+d) ? This is proved very simply by the direct application of perhaps the most fundamental statement in all of Algebra: "If equals are added to equals, the sums are equal."
4
d=3c
It is the formula for the circumference C of a circle where D is the diameter. C = (pi) D
The answer might depend on what c and d are supposed to be!
the answer is a
C = D C = 10 utils, and D = 10 utils
They all equal each other. a = b = c = d = e e = a e = b e = c e = d e = e
As A/B=C/D , So B=(A*D)/C
15 Digits on a Clock Face
c = 6 and d = 7
c
If: a = b+c+d Then: c = a-b-d
6d = c Divide both sides by 6: d = c/d