Until we know what it is, let's call the number ' M ', for 'Mystery number'.
The number . . . . M
The triple of the number . . . 3M
One third of the number . . . . M/3
48 added to one third of the number. . . . M/3 + 48 .
You said that 48 added to one third of the number makes triple the number,
so I can write
M/3 + 48 = 3M
and the rest is easy.
Multiply each side by 3 : M + 144 = 9M
Subtract M from each side: 144 = 8M
Divide each side by 8 : 18 = M
Check:
Is M/3 + 48 equal to 3M ?
(18/3) + 48 ? = ? 3(18)
6 + 48 ? = ? 54
54 = 54
yay !