Complete Question
The complete question is shown on the first uploaded image
Answer:
the value of 
Explanation:
From the question we are told that
The equation is (x + y = 40)
The first value of x is 
The second equation is (0.75x + 1.5y = 40)
So substituting 

=> 
Now substituting y and
into second equation

=> 
So 
Answer:
1375J
Explanation:
The gravitational potential/potential energy of the at the top of the tree which is the energy by virtue of its position.
P.E = mgh
mass = m
Acceleration due to gravity = g
height = h
At the top of the tree, the value of h (height) is high resulting in the gravitational potential. When the cat lands on the ground, the value of h is zero, the the gravitational potential would be zero and all the potential energy have been converted to other forms of energy.
Therefore, the total gravitational potential store is equal to the maximum amount of energy that can be transferred which is equal to 1375J.
Answer:
The cup with 0.5L
Explanation:
To know what amount of water you take into account the specific heat of the water. The specific heat of water is:

Thus, 4186 J of energy are needed to icrease the temperature of 1 kg water in 1°C. Then, more grams of water will need more energy.
You have that one cup has 0.5 L and the other one has 750mL = 0.75L
The second cup of water will need more heat because the amount of water contained in the second cup is greater than in the first cup with 0.5L