Answer:
x=12. B=52
Step-by-step explanation:
In ∆BCD,
<C=45
<D=7x-1
<B=3x+16[as this diagram is a parellelogram so DE II BC so <CBD=<BDE=3x+16 bcz alternate interior angle]
interior angle of triangle=180 degree
<B+<C+<D=180
3x+16 + 45 + 7x-1 = 180
10x + 60=180
10x =180-60
x=120/10
x=12 degree
m<B =3x+16
=3(12)+16
=36+16
m<B = 52 degree
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