Answer:
y = 3
Step-by-step explanation:
-5y + 8 = -7
subtract 8 from both sides
-5y = -15
now, divide -5 from both sides
y = 3
There's only information to answer question C.
We can only know that 32 marbles were chosen. (yellow and black)
Why?
To answer the first two questions (a and b), we need to know the total number of marbles, so, we can only answer the last question (c).
We know that 7/10 of the 20 yellow marbles were chosen.
So, calculating we have:

Also, we know that 18 black marbles were chosen, so, the total of marbles chosen is equal to 32 (yellow marbles and black marbles)

Have a nice day!
Answer:
36 i think
Step-by-step explanation:
Ok, from your picture, it looks like you have a square and a right triangle next to each other
one of the definition of a square is that all 4 sides are equal, and its given to you that the square has a side length of 3
since the triangle shares a side with the square, that means that shared side has a length of 3
ok, now how about determining the unknown length x
well the base has a length of 5, but you also know that when you add the length of the square side plus x, you should get 5
3+x = 5
and you can solve for x (subtract 3 from both sides)
x=2
now how about determining side length y
well since you know this is a right triangle, you can apply pythagorean theorem

where C is the hypothenuse of the triangle, or the longest side
when you substitute the known values (3 and x)
you get
3^2 + x^2 = y^2
since you already know x=2
3^2 +2^2 = y^2
and you can solve for y
any questions?
9+8=8+9 the trick for commutative is there are two m's in commutative right? well no matter where the mm's are it is still the same word so just like the answer is still the same where ever they go.