2.8-(-5.1)
-(-5.1)=5.1
2.8+5.1= 7.9
Is this what you were asking?
Answer:
E (Y) = 3
Step-by-step explanation:
If a 4-sided die is being rolled repeatedly; and the odd-numbered rolls (1st 3rd,5th, etc.)
The probability of odd number roll will be, p(T) = 
However, on your even-numbered rolls, you are victorious if you get a 3 or 4. Also, the probability of even number roll, p(U) = 
In order to calculate: E (Y); We can say Y to be the number of times you roll.
We know that;
E (Y) = E ( Y|T ) p(T) + E ( Y|U ) p(U)
Let us calculate E ( Y|T ) and E ( Y|U )
Y|T ≅ geometric = 
Y|U ≅ geometric = 
also; x ≅ geometric (p)
∴ E (x) =
⇒
= 4 ; also
= 2
E (Y) = 4 ×
+ 2 ×
= 2+1
E (Y) = 3
Try using negative numbers
1.5-6-12n. 1-12n
2.-4+40x-35. -39+40x
3.-36x+6+6. 12-36x
4.40n-32+8n. 48n-32
5.7n-28-6. 34-7n
6.-16+20x+3x 23x-16
7. -2n-16+8. -2n-8
8.25b-25-1. 25b-26
9.-4n+15-6n. -10n+15
-1-3x+6. -3x+5