-9 - 1 = 2/3(-15) need sloved

-10=-10

Step-by-step explanation:

-9-1 =2/3(-15)

-9-1 = - 2/3×15

(cancel the /3 and 15)

-9-1 = -2×5

-10 = -10

7 3/5 = 38/7 hours 
1/2 hour 
7/10 hour 

convert them so they all have the same denominators 

38/7 = 380/70
1/2   = 35/70 
7/10 = 49/70 
 
add 35/70 and 49/70 then subtract from 380/70

35/70 + 49/70 = 84/70
380/70 - 84/70 = 296/70 

296/70 divided into 6 classes 

296/70 divide 6 = 296/70 x 1/6 
= 74/105 x 60 mins
= 42.28571429
each class is approximately 42 mins long