What’s the answer for both questions ?

Dakota earned $7.50 in interest in account a and $18.75 in interest in account b after 15 months. if the simple interest rate is 4% for account a and 5% for account b, which account has the greater principal? explain. to make it a little easier, there is an image. good luck!

What is the greatest number of parts of a circle that can be formed by cutting the circle with 7 straight cuts? (note: the parts do not have to be equal in size)

Ariana starts with 100 milligrams of a radioactive substance. the amount of the substance decreases by 20% each week for a number of weeks, w. the expression 100(1−0.2)w finds the amount of radioactive substance remaining after w weeks. which statement about this expression is true? a) it is the difference between the initial amount and the percent decrease. b) it is the difference between the initial amount and the decay factor after w weeks. c) it is the initial amount raised to the decay factor after w weeks. d) it is the product of the initial amount and the decay factor after w weeks.