What if f(x)=(1/7)(7x), what is f(3)

Me find the missing dimension of a triangle height: 7 in., area: 21^2

Mp model with mathematics explain how the number of text messages dario sent and the cost form an arithmetic sequence. then write an expression to find dario's text messaging bill if he sends n text messages over 250.

The parabola x= √y-9 opens: a.)up b.)down c.)right d.)left