Answer:
x = 15
y = 21
Step-by-step explanation:
*triangle sum theorem*
(6x - 11)° + (81)° + (x + 5)° = 180°
(7x - 6)° + (81)° = 180°
(7x)° + (75)° = 180°
(7x)° = (105)°
x = 15
________________
*vertical angle theorem* *triangle sum theorem*
(6x - 11)° + (4y - 18)° + (y + 14)° = 180°
^
|
15
(79°) + (4y + y) + (14 - 18)°
_________________________
(79)° + (5y - 4)° = 180°
(5y)° + (75)° = 180°
(5y)° = 105°
y = 21
Xy - x - y + 1
explanation: distribute (x-1)(y-1) —> x(y-1) - 1 (y-1) —> xy - x - 1(y-1) —> xy - x - y + 1
About 3,000 books because 105 * 28 = 2940
and 2940 rounded to the nearest thousand is 3000. Hope this helps.