Question 679076
Let X = Kumar's present age
Dollah's present age is 3X

X+12 = Kumar's age in 12 years
3X+12 = Dollah's age in 12 years

th sum of their ages in 12 years
sum means add
will equal 10X

Our equation is:
X+12+3X+12=10X
4X+24=10X
subtract 4X from both sides
24=6X
divide 6 from both sides to get X by itself
X=4

Kumar's present age is 4 years old.
Dollah is 3X   3(4)=12   Dollah's present age is 12 years old.