The number of diagonals of an n-sided polygon is given by the formula D= n/2(n-3). A polygon has 90 diagonals. How many sides does it have?

answer;

the correct answer

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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

answer: (1,3) (3,-1) (5,-5) ?

step-by-step explanation:

45.36 feet per second

step-by-step explanation:

tyrone travels 30 miles in 58.2 minutes.  

1 mile = 5280 feet; this means he travels

30(5280) = 158400 feet in 58.2 minutes.

1 minute = 60 seconds; this means he travels 158400 feet in

58.2(60) = 3492 seconds.

this gives us the unit rate of

158400/3492 = 45.36 feet per second.