14 coins. 140/10 = 14 :) Hope this helped!
Answer:

Step-by-step explanation:
The student used the wrong property of equality.
When you undo a number to get a letter by itself, you should do the opposite operation of the number said. The student subtracted 15 from 22 instead of adding 15 to 22.
Use the addition property of equality to isolate w.

Answer:
0
Step-by-step explanation:
Numbers on balls:
1, 4, 7, 7, 8
Try to find the sum of all numbers:
1+4+7+7+8 = 27
According to the rule of 3, any number is dividable by 3 if the sum of it's individual is divided by 3.
27 is dividable by 3, therefore any combination will result a number with a factor of three.
Prime number is the number that is only dividable by 1 and itself. Therefore, any combination using those numbers are not prime number.
So the probability is 0