Yes, Bobby will have enough money if he saves for 9 weeks. You can find this through either substituting w for 9 in the equation, or solving the equation itself.
Substituting:

Substitute w for 9.

Simplify.

Solve.
255 is greater than 250, so yes, he will have enough money saved.
Solving the equation:

Original Equation

Subtract 30 from both sides.

Divide both sides by 25.
The number of weeks he needs is 8.8. When rounding it up, you get 9.
Answer:
It will be equal to 40
Step-by-step explanation:
We have to compute 
Let first find 3 !
For this we have to use factorial concept
So 3! will be equal to 3! = 3×2×1 = 6
Now According to 6+2 = 8
And now after solving bracket we have to multiply with 5
So 5×8 = 40
So after computation 
So the final answer will be 40
No there isn’t enough water, 975 divided by 70 is 13.92 indicating there would only be enough water for 13 experiments and not 15