Fari,

I am going to solve a similar problem.

Solve for y
8^y = 5 × 2^{(y - 7)}

Since 8 = 2³ this equation can be written

(2³)^y = 5 × 2^{(y - 7)}
2^3y = 5 × 2^{(y - 7)}

Divide both sides by 2^{(y - 7)} to get

2^3y-(y-7) = 5
2^2y+7 = 5

Take the log of both sides to get

log(2^2y+7) = log(5)
(2y + 7) log(2) = log(5)
2y + 7 = log(5)/log(2)
2y = log(5)/log(2) - 7
y = 1/2(log(5)/log(2) - 7)

Now try your problems,
Penny