Answer:
No, none of the number need to be 48 for the mean to be 48. To get a mean, you add up all the number and divide it by the amount of numbers.
Example:
the mean of 10, 79, 42, 88, 19, and 50 is 48, but the actual number 48 was not part of the set.
10 + 79 + 42 + 88 + 19 + 50 = 288
288 ÷ 6 = 48
I am unsure about the very last problem but I can help with the first two
1) (y+1)+4
If we combine the numbers 1 and 4, we get +5 and can isolate the numbers from the variable.
This would give us

2) (6*r)*7
remember that we do not have to explicitly state 6*r
Instead, we can write it as 6r
this helps us get rid of the parentheses
now we can write it as

I hope this helps!:)
Answer:
GI or HJ
Step-by-step explanation:
Diagonals connect non-adjacent vertices.
That is, the diagonal with G as an endpoint will not connect to vertices H or J, but will connect to vertex I. Likewise the diagonal with H as one end will have J as the other end. A quadrilateral has only two (2) diagonals. Of course, each can be named two ways:
GI or IG
HJ or JH
Answer:
Objective Function: P = 2x + 3y + z
Subject to Constraints:
3x + 2y ≤ 5
2x + y – z ≤ 13
z ≤ 4
x,y,z≥0
Step-by-step explanation: