Answer:
#a. $80
#b. $1680
Step-by-step explanation:
We are given;
- Amount invested (principal) is $1600
- Rate of interest is 5%
- Time = 1 year 
We are required to determine the amount of simple interest earned and the amount or balance in the account after 1 year.
#a. Interest earned 
To calculate simple interest we use the formula;
I = (PRT) ÷ 100
Where, P is the principal, R is the rate, T is the time and I is the simple interest.
Therefore;
I = (1600 × 5 × 1) ÷ 100
  = $80
Therefore, simple interest earned is $80
#b. Balance of the account (Amount accrued)
We are going to use the formula;
A = P + I , where A is the amount accrued, P is the principal and I is the simple interest earned.
Therefore;
Account balance = $1600 + $80
                             = $1680
Thus, the account balance after 1 year will be $1680
 
        
             
        
        
        
Twenty three times a number f
        
                    
             
        
        
        
The formula can be written in the form ...
... T = (original temperature) + x·(change in temperature each minute)
The problem statement gives you the original temperature (21 °C) and tells you the temperature after 12 minutes. You have to use that information to figure out the change in temperature each minute.
The change in temperature in 12 minutes is (75 °C) - (21 °C) = 54 °C. That is the change in 12 minutes, so the change in 1 minute will be 1/12 of that:
... 54/12 = 4.5
Using this value in the equation for T, we have
... T = 21 + 4.5x