The first number is 36 and the second number is 12.
Let x be the first number and y be the second number.
The sum of them is 48; therefore x+y=48.
Increasing the first number 3 times is 3x. Increasing the second number 9 times is 9y. When we do this, they are equal, so 3x=9y. We will solve for x so we can use substitution:
3x=9y
3x/3 = 9y/3
x=3y
Now we will substitute this into our first equation:
3y+y=48
4y=48
Divide both sides by 4:
4y/4 = 48/4
y = 12
