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:
f(x) = (x - (-5))^2 + (-18)
Step-by-step explanation:
Given:
f(x) = x^2 + 10x + 7
Rewrite f(x) in vertex form
Solution:
f(x) = ax^2 + bx + c is a quadratic function.
The vertex form of f(x) is a(x - h)^2 + k, where (h, k) is the vertex.
=> f(x) = x^2 + 10x + 7
= x^2 + 10x + 25 - 18
= (x + 5)^ - 18
= (x - (-5))^2 + (-18)
=> f(x) can be rewritten in form of a(x - h)^2 + k, where (h, k) is the vertex, with a = 1, h = -5, k = -18