How to find a missing base

Question

a⁵₌₃₁₂₅

_{above Is an example I found}

_{I don't know the method for finding the missing base...}

Answer 1

a^5 = 3125

a = the 5th root of 3125

3125 = 125 times 25 = 5^3 x 5^2 = 5^5

a = 5

5^5 = 3125

best way to do this is maybe go on online to Desmos

and find the 5th root of 3125

5^5 = 5x5x5x5x5 = 3125