Respuesta :
Remark
You need to assume that the fee is a whole number. It's not stated, but it really should be. That makes your life so much easier if you make that assumption.
Step One
Factor each of the 3 amounts into their common prime factors.
28 = 2 * 2 * 7
21 = 3 * 7
63 = 3 * 3 * 7
Step Two
Pick out the factor that is common to all three amounts.
You can see that it is 7. Each student had to pay 7 dollars in art fees.
Step Three
Find the number associated with the amount that is not a 7.
28 dollars has a 4 along with the 7. 4 students paid on the first day
21 dollars has a 3 along with the 7. 3 students paid on the second day
63 dollars has a 9 along with the 7. 9 students paid on the third day.
So the class size was 4 + 3 + 9 = 16 students in the class, or at least there were 16 paying students in the class.
You need to assume that the fee is a whole number. It's not stated, but it really should be. That makes your life so much easier if you make that assumption.
Step One
Factor each of the 3 amounts into their common prime factors.
28 = 2 * 2 * 7
21 = 3 * 7
63 = 3 * 3 * 7
Step Two
Pick out the factor that is common to all three amounts.
You can see that it is 7. Each student had to pay 7 dollars in art fees.
Step Three
Find the number associated with the amount that is not a 7.
28 dollars has a 4 along with the 7. 4 students paid on the first day
21 dollars has a 3 along with the 7. 3 students paid on the second day
63 dollars has a 9 along with the 7. 9 students paid on the third day.
So the class size was 4 + 3 + 9 = 16 students in the class, or at least there were 16 paying students in the class.