Answer: Well you’re solving for “x,” so you’ll need to isolate this variable. This means we need to “get rid of” the fraction 2/3 that is attached to it. The faction is attached by the operation multiplication, so to remove it we must divide it on both sides. And division with fractions requires the reciprocal. (Try watching an explanation if you’re confused on why division requires reciprocals).
Let 
be the volume of 20% solution, 
the volume of the 60% solution. We want a total volume of 400 mL in the final mixture, so
Each mL of either solution will contribute a corresponding concentration, and in the final mixture we want the 400 mL to have a 40% concentration, which means we should also have
Solve the system and we get 
.
7 that is what t should be
I think it would be C but that’s just my opinion
Answer:
Chord.
Step-by-step explanation:
A chord us any line segment that joins two points on the circumference of a circle.
A diameter obeys that definition.
It's a special chord because it passes through the center of the circle.
