There is no difference, 6rs-(-2rs) if you get rid of the parenthesis you are left with 6rs- -2rs and two negatives make a positive therefore the answer will become 8rs... I hope this helps :)
Answer:
According to logarithmic properties.... The right hand side can be written as
log base 7 (180/3).....which is log base 7 60
So according to the question cancel out the log base 7 from both sides....
Then we get 8r + 20 = 60
That is 8r = 40..
That is r = 5......
Therefore the value of r is 5
i do believe the first one is D but im not sure about the 2nd <span />