if 10 custom engraved pens cost $100, how much will 8 of the same pens cost?

They will cost $80.

Step-by-step explanation:

First, find the out how much 1 pen cost(unit rate).

To do that, divide 100 by 10.

100÷10= 10

So, each pen cost $10.

Now, multiply the cost of 1 pen times 8.

10×8= 80

This concludes that 8 of the same pens cost $80.

12

step-by-step explanation:

a triangle's   full angle is 180 degrees so 180 - 156 = 24. 24/2=12