How do you complete level 15 of rubble trouble moscow

Take your Grabber to the right of the screen - There are 3 Wooden Logs placed here... One short, One long and again one short...
Be careful! Grab the Longest one and lift it across to cover both the wooden pillars to form a bridge.

Now use the grabber to take one of the shorter Logs and drop it on the Right of the longest one, Do the same for the next log placing it slightly further to the right than the last log. They will act as a Counterbalance.

Now set off the Nitro on the barrels. If you have positioned the logs right on top of the wooden pillars, Then as the longest log burns away, It will start to topple but be weighed down and stay in one place... Very Awkward level but simple when you know how.