Geometry. check my answer!
mario’s company makes unusually shaped imitation gemstones. one gemstone had 12 faces and 10 vertices. how many edges did the gemstone have?

a. 23 edges
b. 22 edges
c. 25 edges
d. 20 edges

5=812a+9+3

step 1: simplify both sides of the equation.

5=812a+9+3

5=(812a)+(9+3)(combine like terms)

5=812a+12

5=812a+12

step 2: flip the equation.

812a+12=5

step 3: subtract 12 from both sides.

812a+12−12=5−12

812a=−7

step 4: divide both sides by 812.

812a /812 = -7/812

a= -1/116

so the answer is

a=   -1/116