To solve this problem, we first need to convert all measurements to the same unit.

1 дм = 10 см
5 дм = 50 см
8 м = 800 см
3 м = 300 см

Now let's perform the calculations:

1 дм 2 см + 5 дм 7 см = 12 см + 57 см = 69 см

8 м 8 дм - 3 м 7 дм = 800 см + 80 см - 300 см - 70 см = 810 см - 370 см = 440 см

Therefore, the equation 1 дм 2 см + 5 дм 7 см = 8 м 8 дм - 3 м 7 дм becomes:

69 см = 440 см

These two sides of the equation are not equal, so the statement is false.