First, let's convert every single measurement into feet from meters so we don't have to worry about it later.
We have \(\frac{12m}{ 0.3048 m/ft }=39.3701 ft \) for the height
And we have \(\frac{120m}{ 0.3048 m/ft }=393.7007 ft \) for the length.
Now, we can find the total area of the wall. We do length times height, so we have
\( (39.3701 ft)(393.7007 ft) = 15,500.0359 ft^2 \)
Now, we do some ugly math. We must divide by the gallons.
Since each gallon of paint covers 150, we must do
\(\frac{ 15,500.0359 sq ft}{ 150 sq ft/gallon }= 103.3335 gallons \)
Since you can't actually by a fraction of a gallon, we must round up.
So, we simply have
104 gallons as our answer.
So 104 is our answer.
Thanks! :)