In a convex quadrilateral ABCD, the diagonals are perpendicular to each other. The length of the edges are AB=2017, BC=2018, CD=2019, find the length AD?

The writing is like bold so i can’t see it well

Iwould say 48 bc the line of x is the line of 6 so 6×6=48

The skating rink rented 872 pairs of skates during april and may.why? : if the skating rink rented three times the pair of skates in april during may, they rented 654 skates. 218 x 3 = 654then, if they want to know how many they rented during both april and may, then you just add 654 (may) and 218 (april) to give you 872 pairs of skates for both months.654 + 218 = 872hope this !