Algebraic

As we need to work out the ratio, simply multiply 12 by number of times 18 is greater than 4, ie;

$12 \times \frac{18}{4} = 54$

4N=(12*18) simplifying N=54 orN=(216÷4)

In ratios, Product of extremes=Product of means; So it goes as 4*N = 18 * 12; N= (18 * 12)/4; N= 18 * 3; N= 54

4 : 18 = 0.2222222222222222... and in the answers there is only one number that is bigger than 12 is 54.