4y=24y+105, subtract 4y from both sides:
0=20y+105, subtract 105 from each side:
-105=20y which is the same as 20y=-105, so divide both sides by 20:
y=-105/20=-21/4 (divide top and bottom by 5).
This answer can also be written as a mixed number -5¼ or a decimal -5.25.