Final answer:
To solve the proportion equation a/b = c/d for d, cross-multiply and solve for d by multiplying both sides by bd. The solution is d = cb/a.
Step-by-step explanation:
A fraction is a number which represents a part of a whole and is written as a/b, where a is the numerator and b is the denominator. Two fractions, a/b and c/d, are equivalent when a/b = c/d, which is called a proportion.
To solve the equation a/b = c/d for d, we can cross-multiply and solve for d by multiplying both sides by bd. Therefore, d = cb/a.