Answer:
A = 78.5 cm^2
Step-by-step explanation:
The area of a circle is given by
A = pi r^2
We know r =5 and pi = 3.14
A = 3.14 (5^2)
A = 3.14 (25)
A = 78.5 cm^2
in 20 days 4 half life will be completed
so n = 4
formula :-

A number, a variable, or group of number and variables that are added, subtracted, multiplied, or divided
Answer:
70 cm
Step-by-step explanation:

Answer:
8. $35.10
9. $59.63
10. $13.43
11. $70
12. Take the percent you pay (100-the discount) as a decimal and multiply it by the regular price.
Step-by-step explanation:
For finding the price we pay during a sale, we focus on the percent we pay. If 22% off is the sale, then we spend 78% or 100-22-78. We use this percent byb multiplying the price with a decimal. We convert percents into decimals by dividing the percent number by 100. For example, 78% divided by 100 becomes 0.78.
8. Percent off is 22%. We pay 78%=0.78.
45(0.78)=$35.10
9. Percent off is 33%. We pay 67%=0.67.
89(0.67)=$59.63
10. Percent off is 44%. We pay 56%=0.56.
23.99(0.56)=$13.43
11. Percent off is 75%. We pay 25%=0.25.
279.99(0.25)=$70
12. See explanation above.