Simplify the expression by combining like terms: 4a+7b−2a+b4a + 7b - 2a + b4a+7b−2a+b.
2a+8b2a + 8b2a+8b
6a+8b6a + 8b6a+8b
2a+7b2a + 7b2a+7b
10ab10ab10ab