Answer:
The correct answer is:

Step-by-step explanation:
By evaluating first, and then the mathematical calculation, we have:

Answer/Step-by-step Explanation:
Given:
a = no. of DVDs
b = no. of CDs
Total cost ($) for DVDs and CDs = 
a. The cost for 1 DVD = 2.5(a) = 2.5(1) = $2.5
The cost for 1 CD = 2(b) = 2(1) = $2
b. Total cost for 4 DVDs and 4 CDs:
Substitute a = 4, and b = 4 into the equation.


Total cost for 4 DVDs and 4 CDs = $18
c. To find out if $20 would be enough to buy 6 DVDs and 3 CDs, substitute a = 6, and b = 3 into the equation. Solve for the total cost to see if it equals $20 or is less than $20. If it's greater than $20, then it won't be enough.


6 DVDs and 3 CDs cost more than $20, therefore, $20 is not enough.
Answer:
I
Step-by-step explanation:
3x-5+7x+5+90=180
x=9
Answer:
Rotation of 180° clockwise around the origin
Step-by-step explanation: if you rotate the first triangle 90 degrees, it will be in the lower quarter, so you need to rotate it 1 more time.
Answer:
$561, yes!
Step-by-step explanation:
after 4 weeks, they will have 21*4=$84 per kid (4 kids). Therefore we need to multiply this by 4. 84*4=$336. You must remeber that they started with $225, so 225+336=$561, which is more than $512, so they can pay for the trip!