SOLUTION: Helen was 13 years old on her birthday and the average age of her four friends was 12 years 2 months. If the average age of all six children was 11 years 5 months, how old was her

Everything is in months in this problem.
There are 12 months in a year.

So Helen is 13x12 = 156 months old.

That's 12x12+2 = 144+2 = 146 months.

So the sum of the 4 friends ages in months is 4x146 = 584 months.

That's 12x11+5 = 132+5 = 137 months.

So the sum of the 6 children's ages in months is 6x137 = 822 months.

   






                                        6
So Paul is 82 months old, which is  12)82 
                                       72
                                       10

6 years and 10 months.

Edwin