Find f(-1) when f is the function given by the rule f(x)= x-2/x-1

Me i’m stuck on all these questions besides the two bottom ones

Bocephus has a bag full of nickels and dimes. if there are 3 times as many dimes as nickels, and he has $\$36.05$ in his bag, how many nickels does he have?

The students in a class were asked how many siblings they have. the data obtained is represented in the dot plot. the number of students who have no siblings is . the number of students who have three or more siblings is .