Jenna has 17 friends.
The equation can be written as:
77 - 4x = 9 where 77 is the total number of toys, 4 is how many toys she gave to each friend, x is the number of friends, and 9 is the toys remaining.
To solve for x, the number of friends:
77 -4x=9
Subtract 77 from both sides
77-77 -4x= 9-77
-4x= -68
Then divide both sides by -4 to isolate x.
-4x/-4 = 1x and -68/-4 = 17.
1x= 17, so the number of friends is 17.