A skating rink can be rented for parties. The total price, p, for g guests can be found using the formula below. p = 69 + 90
Write an equation that shows the same formula rearranged to find g in terms of p.
(Give your response in the form g = ...)

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.