Need help finding the d and also explain please

If t8 = 4 and t12 = −2, find the first three terms of the arithmetic sequence.

An airplane is flying at an elevation of 5150 ft, directly above a straight highway. two motorists are driving cars on the highway on opposite sides of the plane, and the angle of depression to one car is 35 ̊ and to the other is 52 ̊. how far apart are the cars?

Robert has 78 tomatoes and 56 cucumbers he wants to plant them in equal rows how many in each row