Question

solve for b in the proportion.
\\(\frac{3}{4} = \frac{21}{b}\\)
(b = square)
submit

Explanation:

Step1: Cross - multiply the proportion

To solve the proportion $\frac{3}{4}=\frac{21}{b}$, we use the cross - multiplication property of proportions. If $\frac{a}{c}=\frac{d}{e}$, then $a\times e = c\times d$. So, we have $3\times b=4\times21$.

Step2: Simplify the right - hand side

Calculate $4\times21 = 84$. So the equation becomes $3b = 84$.

Step3: Solve for b

Divide both sides of the equation $3b = 84$ by 3. That is, $b=\frac{84}{3}$.

Step4: Calculate the value of b

$\frac{84}{3}=28$.

Answer:

28