15.
10
It is: (5+2)*10 = 70
10 + 10 + 10 + 5 + 5 +1 = 41.
'Sum' is pretty much a synonym for add, and 5+5 or 5 plus 5 is 10.
One method is (10×4)+(5×3) = 55 (or mentally add up from left to right).
(5 feet 10 inches) plus (33 inches) = 2.6162 metres.
30 + 10 + 5 + 5 = 50
5+5=10 5+5=10 10+10+5=25 so the answer is not 20, it is 25 or 5*5
25 as 10+10 is 20 plus 5 is 25
5
165
3 + 4 + 5 + 6 + 9 + 7 + 6 + 8 + 5 + 2 = 55