number 1 = 17
number 2 = 72
number 3 = 24
work:
the three numbers are symbolized as x, y, and z
x + y + z = 113
number 2 (y) is 3 times the third number (z) so
y = 3z
so x + 3z + z = 113
the first number (x) is 7 less than than the third number (z) so
x = z - 7
so z -7 + 3z + z = 113
5z - 7 = 113
5z = 120
z = 24
x = 17
y = 72
Hope this helped :)