The fourth proportional to 5, 35 and x is 84, find the value of x.

Correct option is B

Given:

1st Proportional(a) = 5
2nd Proportional(b) = 35
3rd Proportional(c) = x
Formula Used:
4th Proportional(d) = $$\frac{bc}{a}$$​​
Solution:
According to the formula, 
​$$\Rightarrow \text{4th Proportional (d)} = \frac{b \times c}{a}\\84 = \frac{35 \times x}{5}\\\ \\x = \frac{84 \times 5}{35} = 12\\$$​​