For example if the side that was length 10 in the first triange is length 15 in the second triangle then the proportion is 15/10 = 3/2. Theerefore the side that was length 8 i the first will be 8 * 3/2 = 12 units in the second triangle and the other side will be 4 * 3/2 = 6 units.
Note that if I have missed my guess and picked two sides which were nolt corresponding ni the similar triangle than the proportion will differ. But given this leads to integer units I suspect this I have guessed right.
Hope this helps.