Question

3.13

Two years ago, a father was four times as old as his son. Three years from now the father will be
only three times as old as the son. How old is each at present?

Answer 1

45

Explanation:

45 daw sagot sabi,, la

Answer 2

The son is 12, The father is 45

Explanation:

Let x=son's age now

Then x-2=son's age two years ago

And 4(x-2)=father's age two years ago

So 4(x-2)+2=4x-8+2=4x-6=father's age now

Also x+3=son's age three years for now

And 3(x+3)=father's age three years from now

Now if we subtract 5 years from father's age three years from now, then that will equal father's age two years ago. So:

3(x+3)-5=4(x-2) get rid of parents

3x+9-5=4x-8

3x+4=4x-8 subtract 4 and also 4x from both sides

3x-4x+4-4=4x-4x-8-4 collect like terms

-x=-12 divide both sides by -1

x=12 - son's age now

------------------------------------------------------------------------------------------------------------

4x-6=4*12-6=48-6=42 - father's age now

Two years ago, father was 4 time as old as his son:

4(12-2)=42-2

40=40

also

Three years from now father will only be three times as old as his son

3(12+3)=42+3

45=45