There are 35 boys and 21%C2%A0girls on the Math team. For the next math competition, Mr. Johnson would like to arrange all of the students in equal rows with only girls or only boys in each row. What is the greatest number of students that can be in each row?
To find the greatest number of students that can be in each row, we need to find the greatest common divisor (GCD) of 35 and 21.
Prime factorizing 35, we have 35 = 5 * 7.
Prime factorizing 21, we have 21 = 3 * 7.
The GCD of 35 and 21 is the product of the common prime factors raised to the smallest exponent, which is 7.
Therefore, the greatest number of students that can be in each row is 7. Answer: \boxed{7}.