Answer:
a = 9
Step-by-step explanation:
Simplifying
8.1 = 0.9a
Solving
8.1 = 0.9a
Solving for variable 'a'.
Move all terms containing a to the left, all other terms to the right.
Add '-0.9a' to each side of the equation.
8.1 + -0.9a = 0.9a + -0.9a
Combine like terms: 0.9a + -0.9a = 0.0
8.1 + -0.9a = 0.0
Add '-8.1' to each side of the equation.
8.1 + -8.1 + -0.9a = 0.0 + -8.1
Combine like terms: 8.1 + -8.1 = 0.0
0.0 + -0.9a = 0.0 + -8.1
-0.9a = 0.0 + -8.1
Combine like terms: 0.0 + -8.1 = -8.1
-0.9a = -8.1
Divide each side by '-0.9'.
a = 9
Simplifying
a = 9
Circumference is found with the formula
c = pi × d
d is diameter and we will use 3.14 for pi.
The diameter is the measure across the center of the circle. In the first problem, you are given the radius, so we have to multiply by 2 to get the diameter. Then we can use the formula.
12.4 in × 2 = 24.8 in (that's the diameter)
c = pi × D
c = 3.14 × 24.8
c = 77.872 inches
circumference is 77.872 inches.
Try the other problems on your own. They are just like this one. Just make sure they are giving you the diameter and not the radius. Post if you have problems.
Step-by-step explanation:
the order in which you asked the question is correct
A number - n
five times the number - 5n
nine more than five times the number - 5n+9
The answer is D.
