Should be simple:
Let's take this one at a time.
2x(x-3y)
You'd get:
for the first one.
2nd one:
5y(x-3y)
you'd get:
Put them both together:
Combine like terms.
Your Answer:
4 classes, $52
Do it the long way to check
Answer:
600 L of 30% proof and 400 L of 80% proof is needed
Step-by-step explanation:
Let the amount of 30% smell proof be x while that of 80% smell proof is y
Then;
x + y = 1000 •••••(i)
Also;
30% of x + 80% of y = 50% of 1000
0.3x + 0.8y = 500 •••••(ii)
From i, x = 1000 - y
Put this into ii
0.3(1000-y) + 0.8y = 500
300 - 0.3y + 0.8y = 500
0.5y = 500-300
0.5y = 200
y = 200/0.5
y = 400 L
But x = 1000 - y
x = 1000 - 400 = 600 L
Answer: d. (17, 20)
Step-by-step explanation:
We have the following system of equations:
(1)
(2)
Isolating 
from (1):
(3)
Substituting (3) in (2):
(4)
Isolating 
:
(5)
(6)
(7)
Substituting (7) in (1):
(8)
Isolating :
(9)
Hence, the correct option is d. (17, 20)
Is skipped a number and that's not good
