The formula is correct but I do not see any of the other statements. so yes the formula is true.
For the first one multiply each term by the LCM of 4 and 6, which is 12:-
15x -36 = 2y..................(1)
and second multiply by 5:-
2x + y = 9..............(2)
solving:-
from equation (2) y = 9-2x, substitute in equation (1):-
15x - 36 = 2(9-2x) = 18 - 4x
19x = 54
x = 54/19 = 2.84
so y = 9 - 2(2.84) = 3.32
You are looking for three consecutive integers whose sum is 93. First, divide 93 by 3 and get 31. Go one above 31 and one below. You get 30, 31 and 32 which sum to 93.
