The logarithmic form of the equation y=loga x is equivalent to the exponential form x=ay. To rewrite one form in the other, keep the base the same, and switch sides with the other two values.
If you mean 720/10^3, you do 10*10*10. This equals 1000. Now, do 720/1000. This is 0.72, or 72/100, which is your answer.
X/2 + 5 = -10
x/2 = -10 - 5
x/2 = -15
x = -15(2)
x = -30
