Can anyone tell me the rules for rounding of digits? plz ASAP

If the ones place has a number less than 4, the tens stay the same with a zero in the ones place. If the ones place has a number more than 5, the tens will have another ten. If the ones place has a number 5 in the ones place, then you round the tens to the next ten.

Examples: 37=40       73=70          65=70

`1234567890-=/*-qwertyuiop[]asdfghjkl; '\\zxcvbnm,./+ /

you didn't post any answer choices, so its not 100% clear what your teacher is looking for

however, log(15/7) is equivalent to log(15) - log(7)

i'm using the rule log(x/y) = log(x) - log(y)