The average price of four pairs of shoes are $50 and three of those pairs are $35, $40 and $55, then what is the price of the fourth pair of shoes?

You times $50 by 4 to find the sum of the shoes in total. Then you find the sum of the 3 shoes that you know the value of-

$35+$40+$55=$130

You take this number away from the sum of all 4 pairs of shoes.

$200-$130=$70

The anwser is $70