Can someone please help as I'm not sure how to tackle this step by step? Especially question b, d, g, j, k, l. Not how sure to do it if contains a surd just on its own.

Step-by-step explanation:
√a = 1√a so we can solve them easily:
b) 3√7 -√7= 3√7 - 1√7 =( 3-1)√7= 2√7
d) 5√6 - 2√6+√6= (5-2+1)√6 = 4√6
g) √2+2√2= 3√2
j) √5+5√5 - 3√5 = 3√5
k) 2√3 + √3 - 5√3= -2√3
I) 5√11 + 7√11 - √11 = 11√11