Answer:
<em>Helena can bake 2 loaves of bread and 4 batches of muffins. </em>
Step-by-step explanation:
Suppose, Helena can bake
loaves of bread and
batches of muffins.
<em>She needs 3.5 cups of flour per loaf of bread and 2.5 cups of flour per batch of muffins and she has total 17 cups of flour.</em>
So, the first equation will be: 
<em>She also needs 0.75 cup of sugar per loaf of bread and 0.75 cup of sugar per batch of muffins and she has total 4.5 cups of sugar.</em>
So, the second equation will be: 
<em>From equation(2), we will get.......</em>

<em>Substituting this
into equation (1)...........</em>

When
, then 
So, Helena can bake 2 loaves of bread and 4 batches of muffins.