You can factor these terms by finding their greatest common factor, or GCF. Do this by listing all of their factors.
63: 1, 3, 7, 9, 21, 63
91: 1, 5, 7, 13, 91
So, their GCF is 7. Now, divide both terms by 7 to get the second group of the factorization.
63 ÷ 7 = 9
91 ÷ 7 = 13
So, the final factorization will be (7)(9 + 13).