Answer:
2x+y=15x+y=10
Consider the first equation. Subtract 15x from both sides.
2x+y−15x=y
Combine 2x and −15x to get −13x.
−13x+y=y
Subtract y from both sides.
−13x+y−y=0
Combine y and −y to get 0.
−13x=0
Divide both sides by −13. Zero divided by any non-zero number gives zero.
x=0
Consider the second equation. Insert the known values of variables into the equation.
15×0+y=10
Multiply 15 and 0 to get 0.
0+y=10
Anything plus zero gives itself.
Im guessing those are those brackets?
Answer:

Step-by-step explanation:
The given figure is an isosceles trapezoid, this means that the two non-parallel sides in the trapezoid are congruent. One of the properties of an isosceles triangle is that opposite angles are supplementary. This means that the sum of angles opposite each other in an isosceles trapezoid is (180) degrees. One can apply this here by stating the following,

Substitute,

Inverse operations.

Answer:
Do you mind showing a photo of the table? Otherwise I can't really help. I need to know what her bills are.
Answer:
Because that's how the people made it or wanted it
Step-by-step explanation:
Thx