Answer:
$19:50
Step-by-step explanation:
Write a system of equations to represent the problem. Let x represent the cost of a binder, and let y represent the cost of a notebook.
Grace buys 4 binders and 7 notebooks for $26.50 total, so the equation 4x+7y=26.50 represents how much Grace spends.
Grace's friend buys 3 binders and 6 notebooks for $21.00 total, so the equation 3x+6y=21 represents how much her friend spends.
You can use this system of equations to find how much money Grace and her friend spend on notebooks:
4x+7y=26.50
3x+6y=21
Next, find how much Grace and her friend spent on notebooks. Start by finding the cost of one notebook. Use elimination to solve for y. .
3(4x+7y)=3(26.50)
–
12x+21y = 79.50
–
4(3x+6y)=
–
4(21)
–
12x–24y =
–
84
–
3y =
–
4.50
y = 1.50
Each notebook costs $1.50. Grace and her friend buy a total of 13 notebooks, so multiply to find how much money they spend on notebooks.
13$1.50=$19.50
Grace and her friend spend $19.50 total on notebooks.
If a1=1.6 then:
The solution for all these equations is: q=0.5. We have: a1=1.6, q=0.5 and this is geometric sequence.
