About your photograph 4 in wide and 6in long the photograph is enlarged and their larger is proportional to the original photograph with a larger and has a width of 12 in what is the length of the Enlargement ​

18 inches.

Explanation: A simple way to see this problem is to convert the width and length of the photo into a ratio. Width to Length. Now that ratio would be 4:6

or in other words 4 to 6. Ratios can be written as fractions. In this case 4:6 can be written as 4/6. Now all that is left to do is find the missing number of the next ratio since we know that the next ratio is 12 to unknown number.

Step 1.) Once you convert the ratio into a fraction find your variables.

4/6 = 12/?

Step 2.) Let's change the unknown number to x in value according to algebra.

4/6 = 12/x

Step 3.) Solve using cross multiplication.

4/6 = 12/x

4(x) = 6(12)

4x = 72

4x/4 = 72/4

x=18

Hope this helps.  Let me know if you have any questions.

Your Welcome, :-)