Answer: 9/10
Step-by-step explanation: To add like fractions or fractions that have the same denominator, simply add the numerators and keep the original denominators. So here if we add the numerators we have 4 + 5 which is 9. We put this over our original denominator which is 10.
So 4/10 + 5/10 = 9/10.
Using the model, we count all the shaded pieces together and we get 9/10.