42-20=22 ---- I'm pretty sure that's the answer you're looking for.
1) first pick red 5/9 blue 4/9
2) second pick when red has been picked red now becomes 4/8, blue stays 4/8
2) Second pick when blue has been picked blue now becomes 3/8, red stays 5/8
Mind you, you only need both different colours so:
first pick red 5/9 x sec pick blue 4/8 = 20/72
and first pick blue 4/9 x sec pick red 5/8 = 20/72
add both up 20/72 + 20/72 = 40/72 = 5/9
The answer is A. ( reflection over the x-axis ) because the points start in quadrant 1 and when you flip those points across the x-axis they land in quadrant 3. hope this helps !!
Answer: 1400 students
Explanation:
Total = 4000
Senior = 1/8 x 4000 = 500
Senior not in favor of debate = ( 1 - 1/5) x 500 = 400
Non senior = 4000 - 500 = 3500
Non-senior not in favor of debate = (1 - 5/7) x 3500 = 1000
Total = 400 + 1000 = 1400
