A diner has 645 napkins. 325 napkins are used at lunch. 113 napkins are used at dinner.
Melanie says that
325−113=n
napkins are used in all, and that
645−212=r
napkins are left.
Is her answer reasonable? Explain why or why not.
Part A
Is her answer reasonable?
A.
No, because at least 325 napkins are used. So, 212 is too small a number for n.
B.
No, because she adds the number of total napkins used to find n.
C.
No, because she makes an error in her subtraction.
D.
Yes, her answer is reasonable.
D. Yes, her answer is reasonable.
She correctly subtracts the number of napkins used at dinner from the number used at lunch to find n. And her subtraction to find the number of napkins left is also correct. Therefore, her answer is reasonable.