Answer:
15 black water bottles
Step-by-step explanation:
let w represent white water bottles, and let b represent black water bottles.
set up a system of equations:
w+b=20
w+2b=35
(the top equation shows that the number of white water bottles he sold and the number of black water bottles he sold equals to 20, since it says that the total number of water bottles is 20. the bottom equation shows that white water bottles cost $1, and black water bottles cost $2, and that the total amount of money he got from selling them is $35).
in the top equation, isolate w:
w+b=20
w=20-b
now we do substitution. in the bottom equation, substitute 20-b for w:
w+2b=35
20-b+2b=35
then, solve:
b+20=35
b=15
this means that he sold 15 black water bottles.
I think its d but im not sure
Answer:
Addition
Step-by-step explanation:
1) Add 275 to both sides.

2) Simplify 800 + 275 to 1075.

3) Switch sides.

We need to add in order to solve the equation.
so therefor, the answer is option G.
Technically this is not necessarily true for all. A function has each input mapped to one output, therefore there can be two inputs that have the same output. However, when inverted, the input will have two outputs, which is not a function. For example with (1,3) (2,3) (3,4) (4,5) this is a function but switched (3,1) (3,2) ! Two inputs have the same output, which is not a function!
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