Answer:
62 Kg
Step-by-step explanation:
Let g = weight of Grok last year in kg
m = weight of Grok's mother last year in kg
m = 3g
m-4 = 2(g+9)
since m = 3g
(3g)-4 = 2(g+9)
3g -4 = 2g + 18
3g-2g = 18+4
g = 22
m = 3*22
= 66
Note that:
g+9 = weight of Grok now
m-4 = weight of Grok's mother now
Grok weighs 31 Kg now
Grok's mother weighs 62 Kg now
