Evaluate the expression -1 - 4i/2i and write the result in the form a +bi.

The real number a equals?
The real number b equals ?
Please help!!

Atourist boat is used for sightseeing in a nearby river. the boat travels 2.4 miles downstream and in the same amount of time, it travels 1.8 miles upstream. if the boat travels at an average speed of 21 miles per hour in the still water, find the current of the river.

∠1 and ∠2 are vertical angles. ∠2 has a measure of 63°. what is the measure of ∠1 ? enter your answer in the box.

Apudding recipe requires 2/3 of a cup of milk for every 1 3/4 cups of sugar. what is the unit rate of sugar to milk in the pudding recipe?