For these kinds of expressions use FOIL (first, outside, inside, last).
-2x • 9x = -18x^2
-2x • -3y = 6xy
8y • 9x = 72 xy
8y • -3y = -24y^2
Now combine them all:
-18x^2 + 78xy - 24y^2
Answer:

Step-by-step explanation:
Let
be the number of bags with 8 onions and let
be the number of bags with 3 onions. We have the following system of equations:

Subtracting
from both sides of the first equation, we get
. Substitute this into the second equation:

Therefore, the number of 8-onion bags is:

Thus, the chef got 4 8-onion bags and 3 3-onion bags.
Answer:
b)
Step-by-step explanation:
4X1 + 3X2 less than or equal to 150
<h3>
Answer: Choice A</h3>
Why? Because the denominators are both the same at 2x+8. We can only add or subtract fractions when the denominators are the same. The general rule for adding fractions is

We have numerators A and B added together over a common denominator C. If we didn't have a common denominator, then we'd have to do a bit of algebraic manipulation to get both fractions to a common denominator. It doesn't have to be the lowest common denominator (LCD), though it's often more efficient that way.
Answer:
He started with 180.
Step-by-step explanation:
If 90 is 50% of what he started with, then the other 50% is 90