Answer: She's used 630 minutes.
Step-by-step explanation:
She has 1400 minutes.
She used 45% of them.
1. Convert 45% to decimals. You can do by dividing by 100.
2. Multiply by the total amount of minutes.
Answer and explanation:
Eric's expression is and Andrea's is .
In Eric's expression, 10 represents the amount of substance he begins with. 1/2 is the amount of substance left after each time period (in this case, each week).
Andrea's expression can be written as . The one outside of parentheses represents the initial amount of the substance. The one inside of parentheses represents 100% of the original amount of the substance. 0.2 represents the 20% of the substance that is lost each time period. The variable w in this case represents the number of weeks.
D would be the answer you are looking for