The best thing to do here is to find 1/10th then multiply. To do this, divide your number (80) by 10 80/10= 8 As you're looking for sixth tenths, you need to multiply this by 6 8*6= 48 Therefore, six tenths of 80cm is 48cm Hope this helps :)
you could change 6 tenths to a percentage, multiply 6 tenths by 100 over 1 and you get 60%, and the you get 60% of 80, put 80 over 100 and multiply it by 60 and you get 48cm