Question

The sum of Rodney and his sister is 31 his sister is five years less than three times Rodney's age what is the difference in age between Ronnie and his sister

Answer 1

13

Explanation:

Let r and s represent Rodney's age and his Sister's age, respectively. The problem statement tells us the relationships are ...

r + s = 31

s = 3r -5

Using the second equation to substitute for s in the first, we have ...

r +(3r -5) = 31

4r = 36 . . . . . add 5

r = 9 . . . . . . . Rodney's age is 9

We want to find the difference

d = s - r

Again, substituting for s, we have

d = (3r -5) -r = 2r -5

Using the found value of r, this is ...

d = 2(9) -5 = 13

The difference in ages is 13 years.