Answer:
$76.27
Step-by-step explanation:
Consider the equation for simple interest:
I = P x R x T
I is the interest, P is the principal amount, R is the interest rate, and T is the time in years.
If we had to use the equation using the info given, we will see that I(interest) will be equal to the total amount she owed minused by the principal. (I=A-P)
Therefore, substituting the numbers in, we will get an equation like this
90 - P = P x 6% x 3
P = 90 - 0.18P
P + 0.18P = 90
P = 76.27 ( corrected to 2 d.p.)
Since P principal is also the amount of money she borrowed, the answer is $76.27.