Answer:
7
Step-by-step explanation:
Note the factors of each number. Prime numbers are numbers that can only be factored to itself and 1. Note:
Factors of 1:
1
Factors of 3:
1 , 3
Factors of 7:
1 , 7
Factors of 9:
1 , 3 , 9
Factors of 21:
1 , 3 , 7 , 21
Factors of 63:
1 , 3 , 7 , 9 , 21 , 63
Answer is in the pic above. Theorems used:
Exterior angle theorem
Inscribed angle theorem.

Answer:
That is 6 + n
Step-by-step explanation:
6 is added to an unknown number
Y=29
x+y+78=180
x+29+78=180
x=180-78-29
x=73
z=180-73
z=107
x=73 degrees
y=28 degrees
z=107 degrees
Answer:
one ten was traded for ten ones
Step-by-step explanation:
372 cannot be divided by 3 easily. However, 360 +12 can be divided by 3 easily, so it makes sense to trade one of the seven tens for ten ones. That will leave 6 tens, but give twelve ones.
370 +2 = 360 +12 . . . . where the "+" numbers are the numbers of ones