I'm in middle school (8th grade) and this is relatively easy, for me, so...
if each batch of muffins can make 6 muffins, and she makes 2.5 batches of blueberry muffins which will make 15 muffins, she will need to make 7.5 batches of banana muffins to equal 45 muffins and 45 + 15 = 60 muffins.
Here is the math part of it......
1 batch = 6 muffins
She makes 2.5 batches, 2.5 * 6 = 15 muffins
x*6 = 45
divide 6 by both sides to get this
x = 7.5
She needs to make 7.5 batches in order to make the rest of the 60 muffins
If we were to fold this into a prism, the rectangle on the left would be the base. The short sides of the triangles would fold to meet up with the 5 inch sides of the base. Then the rectangle on the right would fold down and fit between the two triangles, meeting up with the base. Visualizing the shape in 3 dimensions allows us to figure out the lengths of some sides. For example, the short sides of the triangles both equal 5 inches. Also, the long sides of the triangles equal 13 inches and the long side of the base is 8 inches.
The surface area is the area of all the surfaces.
8*5=40
8*12=96
2*(0.5*5*12)=60
13*8=104
Add these up..
40+96+60+104=300 in^2
In exponential decay, the value under the exponent must be less than 1 and more than 0
but wait, we have exponents that are negative values, that's interesting
it's a trick, we need to convert it to form

remember that

also that

therefor

so those ones that have the -x exponent, we need to flip the fraction
first one is 7/4, that is more than1
2nd one has a negative exponent so it becomes (3/4)(5/4)^x and 5/4 is greater than 1
3rd one has negative exponent so it becomes (3/2)(7/8)^x and 7/8 is less than 1
4th one is 9/2 and that's more than 1
3rd one is answer or

is an exponential decay function
100% —- $90
1% —- $90/100
70% —- 90/100 x 70 = $63
sale price: $70