Question

A father's age is three less than two times the son's age. The difference in their ages is 30 years. Find the son's age.

Answer 1

You can set up a systems of equations to solve this problem.

The equation y = 2x-3 represents the father's age where y = The father's age and x = The son's age.

The equation 30=y-x represents the difference between the two ages.

In order to be able to solve a system, the two equations can be in the same form. (They don't need to be it's just easier for me to have them in the same form) One is in standard form (ax+by= c) and the other one is in slope intercept form (y=mx+b where m is the slope and b is the y- intercept).

Lets put the equation y=2x-3 into standard form.

y=2x-3

+3 +3

y+3=2x

-y -y

3=2x-y

We have the two equations 30=y-x and 3=2x-y

Now to solve the system.

30=y-x

3=2x-y or 3=-y+2x

30=y-x

3=-y+2x The -y and y cancel each other out since they are the same term but are the inverse of each other one is neg one is pos.

Your left with

30=-x Now you just combine the two equations. 30+3 and 2x-x

3=2x

33=x The son's age is 33. To Find the Fathers age we would just plug 33 for x into one of the equations to find the Fathers age.

SON'S AGE IS 33