**The easiest way to solve this problem is to start with a hypothetical number of kids that's divisible by 7.** From the question, we know that 4/7 of the class is made up of boys and 3/7 is made up of girls. Since we started with 70, we can say that **40 of the kids are boys in our hypothetical class, and 30 are girls.** Of the girls, we know that 2/3 are younger than 10 are 1/3 are 10 or older. This means that **there are 10 girls older than 10 and 20 girls younger than 10.**

Now, we can use the variable x as a stand-in for the number of boys that are 10 years old or older. The number of boys who are younger than 10 can be represented by the expression 40-x (subtract x from the total number of boys in the class). To find x, we would use the 2:3 ratio. **Plugging in the values we just found, this means that x + 10 divided by (40-x) + 20 should be equivalent to 2/3.**

Simplified, the expression looks like (x+10)/(60-x) = 2/3. Then, x+10 = 40 - (2/3)x, and (5/3)x = 30. With this expression, x comes out to be 18. Now remember, we're looking for the fraction of the boys that are older than or equal to 10 years, so 18 isn't the final answer. **Since our original class had 40 boys total, the fraction we are looking for is 18/40, which can be reduced to our final answer, 9/20.**