(50/9-0.8+22/9)×(7.6÷4/5+12/5×1. In the equation (13.5-35 / 4-19 / 4) / [11 / 2 × (△ 23 / 14) / [11 / 7] = 1 / 30, find the number represented by △

(50/9-0.8+22/9)×(7.6÷4/5+12/5×1. In the equation (13.5-35 / 4-19 / 4) / [11 / 2 × (△ 23 / 14) / [11 / 7] = 1 / 30, find the number represented by △

(50/9-0.8+22/9)×[7.6÷(4/5)+(12/5)×(1.25)]
=[(50/9+22/9)-4/5]×[(38/5)×(5/4)+(12/5)×(5/4)]
=(72/9-4/5)×(19/2+6/2)
=(40/5-4/5)×(25/2)
=(36/5)×(25/2)
=18×5
=90
Solution 2
(13.5-35/4-19/4)÷[(11/2)(△+23/14)÷(11/7)]=1/30
[27/2-(35/4+19/4)]÷[(11/2)(△+23/14)÷(11/7)]=1/30
(27/2-27/2)÷[(11/2)(△+23/14)÷(11/7)]=1/30
0÷[(11/2)(△+23/14)÷(11/7)]=1/30
It can be seen that as long as △≠ - 23 / 14, no matter what △ equals, the above equation does not hold
If △ = - 23 / 14, the above equation is meaningless

() / 2.4 = 3.6 / 1.27.5 / () = 2.5 / 12 2.7 / () = 3 / 9 1.6 / () = 0.5 / 3 / 8 5 / 0.3 = 25 () 5.4 / 6.3 = 18 / () see supplement
4 / 3 = () ratio () = () percent sign = () 95 percent sign = () / () = () ratio（

 ( 7.2)/2.4=3.6/1.2
 7.5/(36 )=2.5/12 
2.7/(8.1 )=3/9 
1.6/ ( 1.2)=0.5/3/8 
5/0.3=25 ( 1.5) 
5.4/6.3=18/ (21 ) 
3 out of 4 = (3) vs (4) = (75%) = (0.75) 95% = (95) / (100) = (19) vs (20)

The simple calculation of 1 / 1 * 3 + 1 / 3 * 5 + 1 / 5 * 7 + 1 / 7 * 9 needs the whole process and explanation to be understood, and can't be copied!

1/1*3=(1-1/3)/2
1/3*5=(1/3-1/5)/2
1/5*7=(1/5-1/7)/2
1/7*9=(1/7-1/9)/2
1/1*3+1/3*5+1/5*7+1/7*9=(1-1/3+1/3-1/5+1/5-1/7+1/7-1/9)/2=(1-1/9)/2=4/9