Dan the detective looked for a number. he found a two-digit number less than 50. the sum of its digits was 12. their different was 4. what number did da find

You can quickly tell it is 48, that's the only possibility

for numbers that you cannot quickly tell, suppose the one's digit is x, and the tens' digit is y

in this case, x+y=12 and x-y=4.

add the two equation to eliminate y: 2x=16, x=8

y=x-4=4

the number is 48