Five years from now Dan's age will be three times the age of his son. Five years ago Dan was seven times as old as his son. What is son's present age?

Step-by-step explanation:

Lets age of father be x and age of son be y

x+5=3(y+5)

x=3y+15-5

x=3y+10

x-5=7(y-5)

3y+10-5=7(y-5)

3y+5=7y -35

35+5= 7y-3y

40=4y

y=10 years son`s age

x = ± 6i

step-by-step explanation:

x^2 = -36

take the square root of each side

sqrt(x^2) = sqrt(-36)

we know sqrt(ab) = sqrt(a) sqrt(b)

x = ±sqrt(36) sqrt(-1)

we know that sqrt (-1) = i

x = ± 6i