<PRE><B>Question 117362</B>
Let x=angle measure of angle B


A trapezoid has 4 sides. So this means that the sum of all 4 angles is 360 degrees. So this means 


{{{A+B+C+D=360}}}


Now plug in the given values



{{{90+x+50+90=360}}}




{{{x+230=360}}} Combine like terms on the left side



{{{x=360-230}}}Subtract 230 from both sides



{{{x=130}}} Combine like terms on the right side


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Answer:

So our answer is {{{x=130}}} 


So the measure of angle B is 130 degrees</PRE>