A student bought 15 stamps, some were 50 yen stamps and some were 80 yen stamps. She paid 960 yen.

Which graph represents the equation y =4x

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)

Which equation shows the variable terms isolated on one side and the constant terms isolated on the other side for the equation -1/2x+3=4-1/4x? a. -1/4x=1 b. -3/4x=1 c. 7=1/4x d. 7=3/4x