If you're only dealing with integers, then the answer is:
[-8 , -3)
If you're dealing with real numbers, then the answer is:
[-8, -3)∪(-3, -2)
Formula: n-2(180)
n = number of sides
6-2(180) = 720 degrees
total cost = membership +cost per class* number of classes
y = 275+5*x
Choice C
21. 1/7 3/8 1/2
23. 3 5/8 3 3/8 3 1/2
25. 1/6 3/4 2/3
Answer: Alvin = 42 yrs , Elga = 21 yrs
Step-by-step explanation:
Let Elga's age be x , and Alvin's age be y ,since Alvin is two times Elga's age , then
Alvin's age = 2x , that is
y = 2x ............... equation 1
The sum of their ages is 63 implies
x + y = 63 .............. equation 2
Solving the resulting linear equations by substitution method.
Substitute equation 1 into equation 2 , we have
x + 2x = 63
3x = 63
x = 63/3
x = 21
Therefore : Elga is 21 years old , then Alvin will be 21 x 2, which will be 42
