Question

Ten year ago father was 12 times as old as his son and 10 year hence, he will be twice as old as his son , find their present age by subsutution method.

Answer 1

let fathers age=x
let sons age=y

fathers age before 10 yrs= x-10
sons age before 10 yrs=y-10
according to question,
x-10=12(y-10)
x=12y-120+10
x=12y-110-----(1)

age of father after 10yrs=x+10
age of son after 10 yrs=y+10
according to question,
x+10=2(y+10)
x+10=2y +20
subsitituting (1)
12y-110+10=2y+20
12y-100=2y+20
12y-2y=20+100
10y=120
y=120/10
y=12

therefore,x= 12y-110
x=12(12)-110
x=144-110
x=  34