Ninety percent of the ninth grade students at richbartville high school take algebra. if 180 ninth grade students take algebra, how many ninth grade students do not take algebra?
give answer and explain how to do it i'm so confused!

With these: 18/36 = 1/? missing number change 1 5/8 to improper fraction. change 19/5 to a mixed number.

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.

Rewrite the following quadratic functions in intercept or factored form. show your work. y = 4x^2 - 19x- 5