Hi, I really need help with this. If you can't explain, can you tell me where to start? Or what the formula is? I'm really confused. The midpoint of line segment FG is located at (1, -1).

The coordinates of F are (a-b, a+b).

The coordinates of G are (a+1, -2b).

Solve for a and b and show that the midpoint is correct.

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.