Answer:
3
Step-by-step explanation: if he has 2 rows of four on each page and 13 pages 8 * 13 is 104 and 107 - 104 is 3
(opposite angles in a parallelogram)
(subtraction)
(angles in a triangle add to 180 degrees)
(adjacent angles in a parallelogram are supplementary)
(subtraction)
(angles in a triangle add to 180 degrees)
(angles on a straight line add to 180 degrees)
Answer:
13
Step-by-step explanation:
3 x 3 = 9
7 + 3 = 10
7 + ? = 3 + 7 + 3 + 7
7 + ? = 20
? = 13