Can someone answer all of them or at least one please. Thank you :)

1. Solve the equation below for the variable (y):
2x + 5y = 20
A. y = 20 - 2x / 5
B. y = 18x / 5
C. y = 5 (20 - 2x)
d. y = 2x - 20 / 5


2. Substitute r = 3 and h = 5 into the formula V = πr^2h then evaluate
A. 235.5
B. 47.1
C. 141.3


3. In a formula, any operation we can do to a number can also be done to a variable.
True or False?