PLEASE HELP (i dont know whats going on...) {75 points} Suppose you have n items from which you choose r at a time. Explain why you must divide the number of permutations n!/(n−r)! fraction n factorial , over open n minus r close factorial end fraction by r! to find the number of combinations n!/r!(n−r)!

The axis of symmetry for the graph of the function f(x)=1/4^2+bx +10 is x=6. what is the value of b?

The table represents a linear function. what is the slope of the function? –6 –4 4 6

If m∠abc = 70°, what is m∠abd? justify your reasoning.  using the addition property of equality, 40 + 70 = 110, so m∠abd = 110°.  using the subtraction property of equality, 70 − 30 = 40, so m∠abd = 30°.  using the angle addition postulate, 40 + m∠abd = 70. so, m∠abd = 30° using the subtraction property of equality.  using the angle addition postulate, 40 + 70 = m∠abd. so, m∠abd = 110° using the addition property of equality.