I am currently studying engineering level 3 NVQ and have been having problems with logarithms, the problems I have been given I don't understand these are:

Use laws of logarithms methods to simplify and evaluate the equation given:

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

also another problem is

Simplify 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

Thanks in advance