Let the legs each be x cm, and let the base be y cm.
Thus, we have:
2x + y = 75 --- (1)
x - 7 = y + 2 --- (2)
From (2), we have:
x - 7 = y + 2
y = x - 9 --- (3)
Substituting (3) into (1), we will get:
2x + x - 9 = 75
3x - 9 = 75
3x = 84
x = 28
Substituting 28 into (3), we will get:
y = 28 - 9
y = 19
Hence, the original base of the triangle is 19 cm