The mistake is
3/5/5/3 =-3/5 this is the mistake
but the answer is
3/5/5/3=3/5×3/5=9/25
The next one would be 8:20 or 2:5 and many others, these are just a few
Wouldn’t number seven be
2a+2b because of the distributive property?
Because 35 is divisible by 7, but 23-21=2, so it becomes 25, which 7 is not a factor of. therefore, it is not divisible by 7.
The answer is b , because 2/3 has more numbers in its decimal than the others