Do this both combinatorially AND from set theory.？?

Consider the town of Surrey, where roads are labeled numerically and streets run NS whereas avenues run EW, ascending order from S to N, and W to E, respectively. Provide an upper bound to the number of different routes there are from the corner of Guildford Mall at 152nd St. and 104th Ave to the Skytrain station at King George (136th St. and 100th Ave.). Do this both combinatorially AND from set theory.