Answer:b=-10.5, a=31.5
Step-by-step explanation: 3b=-a , -3b=a
a+b =21
-3b+b = 21
-2b=21
b=-10.5
a=-3b
a=-3*-10.5=31.5
45 degrees and 45 degrees
<45 and >45
>45 and <45
B(You survey every 10th student entering school to find out the amount of time it takes them to get to school) is a good survey
So, Bob needs 2 cups of concentrate (I'll use the variable c to shorten it) for every 3.5 cups of water (w). When he has 6 cups of c, he has three times the original recipe, and therefore we need 3w as well.
3.5x2=6+1=7. So we need 7 cups of water.
Now, 6 cups of concentrate + 7 cups of water = 13 cups of orange juice.
Bob can make 13 cups of orange juice.
Hope I helped!
