First you’d look for ones units that add up to 7, so in this case (5)4 and (6)3
Add 54 and 63 to get 117
Subtract 117 from 177 to get 60
25 and 35 equal 60 (I just know that from common knowledge I have no idea how to explain that in words)
So 25 + 35 + 54 + 63 = 177
