Find the value of x for which the figure is the given special parallelogram

All the corners of a rectangle is equal to 90 degrees. So you need to set (x-1) and (2x+10) equal to 90 and then solve for x. 

(x - 1) + (2x + 10) = 90
Combine the like terms...
3x + 9 = 90
Subtract both sides by 9...
3x + 9 - 9 = 90 - 9
3x = 81
Divide both sides by 3...
3x = 81
(3x) / 3 = 81 / 3
x = 27

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 !