Answer
Find out the what fraction of the sandcastle did they build together .
To prove
Let us assume that the fraction of the sandcastle they build together be x .
As given


Than the equation becomes

L.C .M of (3,7) = 21
solving


Therefore the fraction of the sandcastle did they build together be

Hence proved
10% of 65
Of means multiply
=0.1 x 65
=6.5
Or you can use another way which is (part/whole) *(percent/100)
Whole=65
Percent=10
And part(part of 65)=unknown
(X/65)* (10/100)
Cross multiply
x= 6.5
So 10% of 65 is 6.5
Hi i need more informacion :)01927. i tgink is octagon
There are three more angles with the same measure. A pair of corresponding angles and a pair of vertical angles.