5 / 7 + 5 / 6 + 2 / 7 + 1 / 6 = 1 / 15 * (1 / 3 + 1 / 12) 1 / 4 / (3-5 / 13-8 / 13) 4 / 9 / [5 / 6 - (1 / 6 + 1 / 3)] It's a process

5 / 7 + 5 / 6 + 2 / 7 + 1 / 6 = 1 / 15 * (1 / 3 + 1 / 12) 1 / 4 / (3-5 / 13-8 / 13) 4 / 9 / [5 / 6 - (1 / 6 + 1 / 3)] It's a process

5/7+5/6+2/7+1/6=（5/7+2/7）+（5/6+1/6）=1+1=21/15*(1/3+1/12)=1/15（4/12+1/12）=1/15*5/12=1/361/4/（3-5/13-8/13）=1/4/（3-1）=1/4/2=1/84/9/【5/6-（1/6+1/3）】=4/9/（5/6-1/6-1/3）=4/9/（4/6-1/3）=4/9/（...

Simple operation, 4 / 15 / (1 and 4 / 9-2 / 3 * 5 / 6) + 1 / 5

First of all, it's a primary school student. First of all, your writing method is not standardized. If I understand it correctly, it's like this: step one, the first calculation in brackets (13 / 9-5 / 9) = 8 / 9 is not a problem. Step two, except that the multiplication of variables (4 / 15) * (9 / 8) = 3 / 10, step three, 3 / 10-1 / 5 = 1 / 10. Don't be like me when you write. I'm helping you sort out your ideas

Define an operation: 1 * 3 = 6 2 * 2 = 4 3 * 4 = 15 5 * 5 = 20 Q: 6 * 9=
If you have any problems with tutoring, please help me,

Ha ha, I found it!
a@b= (a+b)(b div 2)+b-a
Div is the quotient of division
Substitution verification:
1@3= (1+3)(3 div 2)+2=4*1+2=6
2@2= (2+2)(2 div 2)+(2-2)=4*1+0=4
3@4= (3+4)(4 div 2)+(4-3)=7*2+1=15
5@5= (5+5)(5 div 2)+(5-5)=10*2+0=25
Are established
therefore
6*9=(6+9)(9 div 2)+(9-6)=15*4+3=63