Answer:
The solution of this system of equations is (3 , -8)
Step-by-step explanation:
The given system is
x + 2y = -13
12x + 5y = -4
We make x the subject of the first equation and put it into the second:

We put this expression for x into the second equation
12(-13-2y)+5y=-4
-156-24y+5y=-4
-24y+5y=-4+156
-19y=152
y=-8
We substitute y=-8 into x=-13-2y to get:

The solution of this system of equations is (3 , -8)
Answer:
2.5 pounds per book
Step-by-step explanation:
Set up a proportion
20 copies / 50 pounds = 1 copy / x pounds
Cross multiply
20x = 50
Divide both sides by 20
x = 2.5 pounds
I hope this helped and please mark me as brainliest!
405=25n+80
405-80=325
325÷25=13