5 × 1 / 5 ／ 5 × 4 / 5 = (8 / 9 + 2 / 3-2 / 27) × 27 = 4 / 85 ／ 1 / 86 =? 9 / 17 × 1 / 7 + 5 / 17 ／ 7 = simple calculation

5 × 1 / 5 ／ 5 × 4 / 5 = (8 / 9 + 2 / 3-2 / 27) × 27 = 4 / 85 ／ 1 / 86 =? 9 / 17 × 1 / 7 + 5 / 17 ／ 7 = simple calculation

5×1/5÷5×4/5=1÷4=1/4
（8/9+2/3-2/27）×27= (8/9+6/9-2/27)×27=(14/9-2/27)×27=42-2=40
4/85÷1/86=4/85×86=344/85
9/17×1/7+5/17÷7=9/17×1/7+5/17×1/7=1/7×(9/17+5/17)=1/7×14/17=2/17

Simplify ratio and calculate ratio, 6:8 78:52 0.45:0.25 3.5:2
The ratio is 6:8 78:52 0.45:0.25 3.5:2.5 0.24:0.2 15 tons: 2750 kg

3:4

How to distinguish 3.52-2.5/0.4

3.52-25/4=3.52-6.25=-2.73

How to simplify 3.67 + 0.25-3.67 + 0.25?!?!
It should be simple

3.67+0.25-3.67+0.25
=(3.67-3.67)+(0.25+0.25)
=0+0.5
=0.5