(100 + __ )+ 290 - 67.0034 = 411.9966
First add 67.0034 to both sides:
(100 + __ )+ 290 = 479
Now subtract 290 from both sides:
(100 + __ ) = 189
Subtract 100 from both sides:
189-100 = 89
The missing value is 89
