On Thursday she cycled 88 km per hr...for 4 hrs
88/4 = 22 km per hr
On Friday, she cycled 3 km per hr faster
22 + 3 = 25 km per hr <==
Answer:
y stands for 21 in this equation.
Step-by-step explanation:
2y - 7 = 35
2y = 42
y = 21
If

is left, that means

was spent. So

of the total amount is equal to 39.. Let's say x to the total amount.
T(t)=e−kt(∫ekt[KM(t)+H(t)+U(t)]dt+C)
M is the outside temperature, H is other things that affect temperature
in the tank(0 in this case), and U is the solar panel. K comes from the
time constant, and should be the inverse of the time constant I believe.
T is temperature, t is time.
T(t)=e−164t(∫e164t[164(80)+4t]dt
After integrating I keep getting
−16304+256t+Ce−164t
I calculate C to be 16414 setting t equal to 0 and using the initial conditions