Marty and stewart are stuffing envelopes with index cards. they are putting index cards in each envelope. when they are finished, marty has 15 stuffed envelopes and 4 extra index cards, and stewart has 12 stuffed envelopes and 6 extra index cards. write an expression in standard form that represents the number of index cards the boys started with. explain what your expression means.

The required expression is s = m + n

Step-by-step explanation:

Let m be the number of index cards stuffed in the envelopes and n be the number of extra index cards.

Let s be the total number of index cards.

Then, s = m + n represents the number of index cards the boys started with.

For Marty,

He has 15 stuffed envelopes and 4 extra index cards.

So, m = 15, n = 4

Therefore, s = 15 + 4 = 19

Marty started with 19 cards.

For Stewart,

He has 12 stuffed envelopes and 6 extra index cards.

So, m = 12, n = 6

Therefore, s = 12 + 6 = 18

Steward started with 18 cards.

answer: it is a.,b.,d.

step-by-step explanation: