Final answer:
Jill and Jack could not have possibly eaten 13.75 brownies if they only had 10. There appears to be a mistake in the problem as posed.
Step-by-step explanation:
The subject here is about the topic of subtraction. To calculate how many brownies are left, we first convert the fractions that describe how many brownies Jill and Jack ate into mixed fractions or whole numbers to make the calculation easier.
Jill ate (13)/(4) brownies, which is 3.25 in decimal form. Jack ate (21)/(2) brownies, which is 10.5 in decimal form.
If we add these two numbers together, we find out that they ate 13.75 brownies together. However, they only had 10 to start with. That means that Jill and Jack could not have possibly eaten 13.75 brownies if they only had 10. Therefore, there appears to be a mistake in the problem as posed.
Learn more about Subtraction