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
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Answer:
1~30
2~3
3~40
4~70
5~90
6~90
7~80
Step-by-step explanation:
subtract the total revenue from the total cost
Answer:
5
Step-by-step explanation:
-6x +10x = 20
4x=20
x=20/4
x=5
Answer:
f^-1 (x)=1/2x+5
Step-by-step explanation:
y=2x-10
x=2y-10
2y=x+10
y=1/2x+10/2
y=1/2x+5
Answer:
80
Step-by-step explanation: