A two digit positive integer can be expressed as 10x+y, where x is the tens digit and y is the ones digit. For example, 37 = 3(10)+7.
So, 10x+y = 4(x+y) and 10x+y = 3xy
10x+y = 4x+4y
6x = 3y
y = 2x
Since y = 2x and 10x+y = 3xy, we have 10x+2x=3x(2x)
12x = 6x2 6x2-12x = 0
6x(x-2) = 0 x = 0 or x = 2
Since x can't be zero, x = 2
y = 2x = 4
The number is 24.