1. 35log[base 6](x) = 18
My answer: x = 6^18/35
2. 6^(-0.2x) - 3 = 7
A bit stuck on this one. I get as far as 6^(-0.2x) = 9, but I'm a bit lost at finding the x?
3. 7log[base 5](x) - 3 = 15
My answer: x = 5^12/7
1. is correct.
2. is incorrect
$\displaystyle 6^{-0.2x} - 3 = 7$
$\displaystyle 6^{-0.2x} = 10$
$\displaystyle -0.2x = \log_6{10}$
$\displaystyle x = -5\log_6{10}$.
3. is also wrong.
$\displaystyle 7\log_5{x} - 3 = 15$
$\displaystyle 7\log_5{x} = 18$
$\displaystyle \log_5{x} = \frac{18}{7}$
$\displaystyle x = 5^{\frac{18}{7}}$.