The topic titled "Distributive property with variables (negative numbers)" allows students to enter mixed numbers, but marks them wrong even when mathematically equivalent to the simplified improper or decimal. Usually, there is a prompt to enter the answer in a specific way if the equivalency isn't going to be accepted. This is a 7th grade topic, which is when students are just learning to transition fluently between these equivalencies, so it is confusing them to have a mathematically correct answer and be marked wrong. I think it is fine to require a specific form of a number, but that needs to be clarified in the directions so that students don't think they've solved the problem incorrectly.

Here is an example of a student's answer vs. what was expected:

I tried it myself to see if the student was ignoring the directions:

It wasn't mentioned in the directions and the pop-up didn't indicate what was wrong with my answer.

I started playing around with different forms of numbers to test out what would and wouldn't be accepted:

Not simplifying was also marked incorrect. Again, there should just be a notification that it needs to be simplified instead of fully marking the problem as incorrect.

It does allow simplified improper fractions and decimal equivalencies.

I can see value in accepting any form of the number and I see value in only accepting specified values, so I'd be fine with either. I just don't like that the student is left trying to figure out why they're being marked wrong with no directions or notification giving them a chance to correct the "error" without being penalized.