Dakota earned $15.75 in intrest in account a and $28.00 intrest in account b after 21 months. If the simple intrest rate for 3.0% for account. A and 4.0% for account b, which account had the greater principal? Explain

Answer: Account B had the greater principal because $400 is greater than $300

Step-by-step explanation:

The formula for simple interest is expressed as

I = PRT/100

Where

P represents the principal

R represents interest rate

T represents time

Considering the investment in account A,

I = $15.75

R = 3%

T = 21 months = 21/12 = 1.75 years.

15.75 = (P * 3 * 1.75) / 100 = 0.0525P

P = 15.75/0.0525 = $300

Considering the investment in account B,

I = $28

R = 4%

T = 21 months = 21/12 = 1.75 years.

28 = (P * 4 * 1.75) / 100 = 0.07P

P = 28/0.07 = $400