For 1 hour:
- Jennifer can clean 1/2 of her room;
- John cal clean 1/5 of her room.
Both can clean: 1/2 + 1/5 = 5/10 + 2/10 = 7/10
1 hour -------- 7/10
x hours---------- 1
x = 1 : 7/10 = 10/7 h = 1.42857 h ( or 1 h 25 min 43 s )
For this case we have:
Cost of manufactures of T-shirts 
where x represents the number of T-shirts
Part A:
Substituting
in the total cost equation you have to:

Thus, the cost of 8 shirts will be 
Part B:
If
then

Thus, the cost of 12 shirts will be 
Answer:

Answer: 81
Step-by-step explanation: Because, (-3)^4=-3*-3*-3*-3=-(-81)=81
Answer:
1. -2
2. add 25/4
3. sub 25/2
4. 5/2
Step-by-step explanation: