I just kept switching around the numbers till the sixes were separated by a factor of 1,000. This means that if the 6 is in a place, that if you multiply the 6 by 1,000, you'll get the place that the other 6 is in.
For 63,363, there is one 6 in the tens place and one in the ten thousands place. 60 x 1,000 = 60,000, which is where the first 6 is in. They are separated by x1,000.
For 36,336, there is a 6 in the ones place and a 6 in the thousands place. 6 x 1,000 = 6,000, and there is a 6 in the thousands place. They are separated by x1,000.
First you would solve 4x=28. Divide both sides by 4 and you'll get x= 7. Then you plug in the 7 in replacement for the x in the equation, 29-5x and you'll get as an answer -6!!