Yes. You certainly can! The numerator and denominator have 7 as a common factor.
No.
no
Yes.
You simplify by finding a common factor of the two numbers greater than 1. In other words, you look for another number (greater than 1) which evenly divides into both the numbers in the fraction. 21 and 28 both divide by 7 to give 3 and 4 respectively. So we can simplify to 3/4.
28/336 = 1/12
a/7 + a/4 = 4a/28 + 7a/28 = 11a/28
To simplify 28 / 35, you divide by the GCF of 28 and 35. The GCF is 7, so 28 / 35 / 7 = 4 / 5.
No, you can't, believe
12/28 = 3/7 = 0.428571428
3/7
4/7
6/21 = 2/7 simplified