Use the picture were it says a, b, c, d those are the steps

What is the midpoint of the segment below? (-4,-7) (5,6)

If the value of cos330°is√3/2 then find cos 165°.

Ascientist has 50 grams of a radioactive element. the amount of radioactive element remaining after t days can be determined using the equation (1) after two days the scientist receives a second shipment of 50 grams of the same element. the equation used to represent the amount of shipment 2 remaining after t days is 10) - 50 which of the following is an equivalent form of the expression for the amount remaining in shipment 2? what’s the answer?