This looks like: 
To solve this problem, you'll want to use the AC method to factor x^2+7x-30.
After factoring your expression will look like this:

Cancel out the x+10 because they are common factors, so you are just left with the simple x-3.
Answer is:
x - 3
Answer:
(6)=120°
(10)=72°
(20)=36°
Step-by-step explanation:
(n-2)×180°
(6-2)×180°=720°
6÷720°=120°
10÷720°=72°
20÷720°=36°
Let x represent the number of liters of 50% acid Theresa puts into the mix. The the number of liters of 30% acid will be (420-x). The total amount of acid in the final solution will be ...
0.50x + 0.30(420-x) = 0.45(420)
0.20x + 126 = 189 . . . . . . . . . . . . . . . simplify
0.20x = 63 . . . . . . . . . . . . . . . . . . . . . subtract 126
x = 63/0.20 = 315 . . . . . . . . . . . . . . . liters of 50% solution
(420-x) = 420-315 = 105 . . . . . . . . . liters of 30% solution
Theresa should mix ...
105 liters of 30% solution
315 liters of 50% solution
An acute angle is infact 90 degrees, therefore your answer is correct.
Answer: 3/2
Step-by-step explanation: