Hi
You are having 1 equation with 3 unknowns. It will have many solution. You can use vpasolve function to solve this, it will give one of the possible solution. For more information, refer this documentation of vpasolve. For unique solution, you can provide 3 equations as well. Consider an example below:
syms i j
e1 = 5^i+7^j==800;
e2 = 6^i+4^j==900;
vpasolve([e1,e2],[i,j]) %gives value of i and j
Hope it will help!
