I need to use laws of logarithms methods to simplify and evaluate these equation

5^{n}= 7 x 2^{n}, rearrange and make n the subject

θ = 250 x e^{-0.05 x t }and make t the subject

and continuing from that

what is the value of t when θ = 195^{◦}C

I need log to the base 10 to be used preferably