Question

solve for d in the proportion.
$\frac{10}{21}=\frac{20}{d}$
$d = square$

Explanation:

Step1: Cross - multiply

$10\times d=21\times20$

Step2: Simplify the right - hand side

$10d = 420$

Step3: Solve for d

$d=\frac{420}{10}=42$

Answer:

$42$