There is a set of formulas: 1 + 1,2 + 3,3 + 5.1 + 7,2 + 9,3 + 11,1 + 13. So the formula of drink is 1997, the () formula from left? The sum of the 1999 formula?

There is a set of formulas: 1 + 1,2 + 3,3 + 5.1 + 7,2 + 9,3 + 11,1 + 13. So the formula of drink is 1997, the () formula from left? The sum of the 1999 formula?

2+1995=1997
So it is item (1995 + 1) / 2 = 998
1999 mod 3 =1,1999*2-1=3397
So item 1999 is
1+3397

Calculate 4 / 5 * (- 5 / 13) - (- 3 / 5) * (5 / 13) - 5 / 13 * (- 1 3 / 5) and use the law of multiplicative distribution to reverse application

Four fifths * (- five fifths) - (- three fifths) * (five fifths) - five fifths * (- 1 and three fifths)
=5 / 13 * (- 4 / 5 + 3 / 5 + 1 and 3 / 5)
=5/13*7/5
=7/13

What's five and a half times two thirds?

11 / 3