Geometry! ! db¯¯¯¯¯ is a diagonal of parallelogram abcd . what is the measure of ∠adb?

Remark
The way to do this problem is to find ADC first and then subtract <BDC from it. 

Argument
A parallelogram has the property of having consecutive angles = to 180 degrees. That means that <DAB + <ADC = 180 

Since <DAB = 105o then <ADC = 180 - 105 = 75

However, <ADC = 75 and <BDC = 35
<ADC  = <ADB + <BDC
75 = <ADB +35 Subtract 35  from both sides 
75 - 35 = 40 

<ADB = 40 Degrees <<<<<< Answer