S 11
=
11
∑
k
=
1

6
+
(
k
−
1
)
2
S
11
=
∑
k
=
1
11
6
+
(
k
-
1
)
2

Frank has a devised a formula for his catering business that calculates the number of meatballs he needs to prepare. the formula is m=4a+2c, where c=number of children; m=number of meatballs; a=number of adults. how many meatballs are required for a party of 10 adults and 5 children?