3r/4= 1/8 what's the value of r

Me! i really need to get this right before 9. prove the divisibility of 7^6+7^5-7^4 by 11. use factoring so you get a number times 11. just tell me the number. i need this done asap

The number of 8th graders who responded to a poll of 6th grade and 8 th graders was one fourtg of the number of 6th graders whi responded if a total of 100 students responddd to the poll how many of the students responded were 6 th graders

Pls never taught i’m really confused and i rlly need