Answer:
SA = π3^2 + π3(7.5)
Step-by-step explanation: r is radius and L
is r*l/2
so 3*5/2=15/2=7.5
seriously look at a problem more carefully and memorise your formulas!
Step-by-step explanation:

Answer:
3.5
Step-by-step explanation:
The lcd would be 10x^3y^3
Answer:
a) 
b)
Step-by-step explanation:
Data
Brine a (Ba)

Brine b (Bb)

we have that per every minute the amount of solution that enters the tank is the same as the one that leaves the tank (15 Lt / min)
, then the amount of salt (y) left in the tank after (t) minutes: 
Finally:
a) 
b) 
being y(t) the amount of salt (y) per unit of time (t)