Heather bought enough shells to make x necklace each necklace holds 16 shells Heather has made 10 necklaces Is 16x+10 a reasonable way to represent the number of shells that Heather has left to make necklaces with Explain your answer

No, because in 16*+10 we don't know what 17 is supposed to be multiplied by. But 16*10 is because we are trying to figure out how many shells she got so with 16 shells on 10 necklaces we know to multiply because the problem calls for more than one.