Why could a single translation map one of the long rectangular benches
onto the other long rectangular bench, but not map one short
rectangular bench and flagpole onto the other short rectangular bench
and flagpole?

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

the answer is c: divide the arc's degree measure by 360°, then multiply by the circumference of the circle.