Question

Need help with 22 I don’t understand

Answer 1

This is going to be hard to draw, but you just substitute Morning mugs for x and solve, and Morning glasses for y and solve. You do the same for the night mugs for x and solve. 

For A solve it in a way that if you substitute X and Y in a way it will turn out to be 23 or 16 in the correct Situation. 
 
For B substitute the X and the Y so it will match up correctly. 

Answer 2

I don't understand part A for question 22 but to find the cost of the mugs, you have to isolate the variable.
1:  5x  +  4y  = 23
2:  4x  +  2y  = 16
step 1. 1-2= (5x - 4x) + (4y - 2y)= 23 -16
                      x + 2y =7
                      x = 7 - 2y
x is equal to 7 - 2y. Next you have to find out what y is.
1:  5x + 4y =23
     5(7 - 2y) + 4y = 23
     35 - 10y + 4y = 23
     35 - 6y = 23
     6y = 35 - 23
     6y/6 = 12/6
     y=2
Now that you know what y is, you have to figure the rest for x.
x = 7 - 2y
   = 7 - 2(2)  <---- (y= 2)
   = 7-4
   = 3
Now you know that x=3 and y=2.
Therefore, a mug costs $3 and a glass costs $2.