Hello, Mona,
The expression given already has a common base, 7.
73x-1=7-2x+14
Please correct this if a different expression was intended.
Assuming it is correct, since the bases are the same, we can say the exponents are equal to each other.
3x-1 = -2x + 14
5x = 15
x = 3
Check the result:
73x-1= 78 = (5764801)
7-2x+14 = 78
I hope this helps,
Bob