Answer:
400
Step-by-step explanation:
The answer is either
or 
To solve: Let's solve your equation step-by-step.
5x2+5x−x2−x=2004
Step 1: Simplify both sides of the equation.
4x2+4x=2004
Step 2: Subtract 2004 from both sides.
4x2+4x−2004=2004−2004
4x2+4x−2004=0
Step 3: Use quadratic formula with a=4, b=4, c=-2004.
x=
−b±√b2−4ac
/2a
x=
−4±√32080
/8
or 
The right answer is Option A.
Step-by-step explanation:
Let,
x be the postcards
y be the large envelops
According to given statement;
14x+5y=12 Eqn 1
10x+15y=24.80 Eqn 2
Multiplying Eqn 1 by 3;

Subtracting Eqn 2 from Eqn 3;

Dividing both sides by 32

Putting x=0.35 in Eqn 1;

Dividing both sides by 5

Therefore, one large envelope costs $1.42
The right answer is Option A.
Keywords: linear equations, subtraction
Learn more about linear equations at:
#LearnwithBrainly
Answer:
95 city and 175 highway miles.
Step-by-step explanation:
The driver gets 20 mpg in city, and 28 mpg on the highway.
An equation that could be written is
20x+28y=270
This equation accounts for the distance traveled.
x+y=11
This equotion accounts for how many gallons were driven.
Multiply the bottom equation by 20, so you can solve the set of equations.
20x+28y=270
20x+20y=220
subtract them
8y=50
y=6.25
now plug this back into x+y=11
x+6.25=11
x=4.75
Now 4.75×20=95 city miles and 6.25×28=175 highway miles.