correct answer is: d) 18

Explanation

Let the fourth proportional be KaTeX parse error: KaTeX doesn't work in quirks mode.
Then, the proportion is KaTeX parse error: KaTeX doesn't work in quirks mode.
The cross-product rule is: –
(Product of extremes = Product of means)
So,
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode.
KaTeX parse error: KaTeX doesn't work in quirks mode. The fourth proportion is: 18
Ans: KaTeX parse error: KaTeX doesn't work in quirks mode.