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How do I solve for X?

How do I solve for X?-example-1

1 Answer

6 votes

All the angles should add up to 360°.

8x+10x+9+21x-12+90=360°

Group like terms together.

So,8x+10x+21x+9+90-12=360

39x+87=360

39x=360-87

39x=273

x=7

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