We can create some equations with this
Let f = Batching's father's age
Let g = Batching's Grandfather's age
Let b = Batching's age
f = g - 26
f = b + 29
f + g + b = 135
To solve this, plugin the solution for one equation into another
f + 26 = g
f - 29 = b
f + f + 26 + f - 29 = 135
3f - 3 = 135
3f = 138
f = 46
Now that we have the fathers age, we can get the other's age
46 = g - 26
46 = b + 29
meaning that f = 72
and b = 17
Batching's father's age = 46
Batching's Grandfather's age = 72
Batching's age = 17