Those are the only ones I can't seem to resolve. Thank you!
resolve x:
1) 9*3^0,51x = 315
2) 10*3^15x+21 =363*2^9x+51
3) log(15x^2) - log(3x) = 4*log(3)
4) log[of base 3]*(15x + 4) = 3
resolve x:
1) 9*3^0,51x = 315
2) 10*3^15x+21 =363*2^9x+51
3) log(15x^2) - log(3x) = 4*log(3)
4) log[of base 3]*(15x + 4) = 3