Question 646075
<pre>
To be in the ratio 4:7, the smaller 2-digit number 
must be an integer times 4 and the larger 2-digit number
must be that same integer times 7.

The largest 2-digit multiple of 7 is 12×7 = 98.  That's B.
So the smaller one, A, must be 12×4 or 48, and that's as
large as A can be. 

So A = 48 and B = 98

The sum of the digits of 48 is 4+8 = 12.

Edwin</pre>