Question

Given that ABCD is a rhombus, what is the value of x?

Answer 1

we know that

The rhombus has the following properties:

Consecutive angles are supplementary

The diagonals bisect the angles

so

$2x\°+2(3x+7)\°=180\°$

Divide by $2$ both sides

$x\°+(3x+7)\°=90\°$

solve for x

$4x=(90-7)\°$

$x=83/4\°$

$x=20.75\°$

therefore

the answer is the option B

$x=20.75\°$

Answer 2

2x + 2(3x+7) = 180
2x + 6x + 14 = 180
8x = 166
x = 20.75

answer
B. 20.75