Marie uses 2.3 oz of nuts for each bag of trail mix she makes. she uses 27.6 oz of nuts in all. how many bags of trail mix does marie make?

2.3 oz per bag, so for x bags you have 2.3x oz total.
The total amount is given as 27.6 oz, so you have 27.6=2.3x.
set equation 
simplify by dividing both sides by 2.3 
solution:  

the law of definite proportions states samples of a compound will always contain the same proportion of elements by mass. in other words, a given compound will always contain the same elements in the same proportions by mass.the law of multiple proportions states when two elements combine with each other to form more than one compound, then the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.

Can you provide the tape diagram?