Answer:
Part A:




Part B:


and 
Step-by-step explanation:
Part A:
The inicial concentration of the lemonade is 50%, and the volume is 4 quarts, and we will add x quarts of a lemonade with a concentration of 100%, so the total volume will be y, and the concentration will be 0.7, so we have that:


Using the value of y from the first equation in the second one, we have:





Part B:
If he shoots a total of ten targets, we can write the equation:

Each stationary target is 2 points, and each moving target is 3 points, so if the total points is 23, we have:

If we subtract the second equation by two times the first one, we have:



⇒ 
Given:
Net of a triangular prism
To find:
Which equation can be used to calculate the surface area of the triangular prism.
Solution:
Using formulas:
Area of rectangle = length × width
Area of triangle = 
Area of left triangle = 
Area of right triangle = 
Area of bottom = 5 × 10
Area of Middle = 12 × 10
Area of top = 13 × 10
Surface area of triangular prism:
Surface area = Area of left triangle + Area of right triangle + Area of bottom + Area of middle + Area of top

Replace multiplication by brackets.

The equation can be used to calculate surface area of triangular prism is
.