ab/d+c=e for d

[math_celebrity]

ab/d+c=e for d

Subtract c from each side:
ab/d+c - c = e - c
ab/d = e - c

Multiply each side by d:
abd/d = d(e - c)
ab = d(e - c)

Divide each side by (e - c):
ab/(e - c) = d(e - c)/(e - c)
d = ab/(e - c)