Muthu had 28 stickers more than Jack. After Muthu had given 2/7 of his stickers to Jack, both of them had the same number of stickers. How many stickers did Jack have at first?

Suppose x is the stickers that Jack have.

—-> x + 28 = 2/7 (x + 28) + x
x + 28 = (2x + 56)/7 + x
2x + 56 = 7 (28)
2x = 196 - 56
2x/2 = 140/2
x = 70
70 stickers