Answer:
3. The equivalent fractions are presented as follows;

4. The equivalent fractions are presented as follows;

5. The reason why it works is because 
Step-by-step explanation:
3. Based on the shaded region of the given figures, the two fractions are equivalent
Mathematically, we can show the equivalency of the two fractions as follows;

Therefore;

4. From the shaded region of the given figure, the fractions are equivalent
Mathematically, we have;

Therefore;

5. The amount of salt required by the recipe = 1/4 teaspoon of salt
The measure of the spoon Jonas has = 1/8 teaspoon
When Jonas adds two 1/8 teaspoons, he gets;

Therefore;

Two 1/8 measuring teaspoons are equivalent to one 1/4 teaspoons and therefore Jonas is able to get the 1/4 teaspoons of salt the recipe asks for b combining two 1/8 measuring teaspoons of salt he has because 1/8 + 1/8 = 1/4.