How to do answer 16, 19 and 21? show me the solutions.

16) the boy is 11 years old

Step-by-step explanation:

16) Let the boy’s present age be b.

b+5 = 4(b-9)^2, or

b+5 = 4[b^2–18b+81] = 4b^2–72b+324, or

4b^2–73b+319 = 0, or

(4b-29)(x-11) = 0, or

b = 11 or 7.25 years. The second value is inadmissible.

So the boy is 11 years old, now.

16

step-by-step explanation:

3/6 chance

step-by-step explanation:

half of the nubers are odd numbers (1,3,5) which in that case if you would be told to simplify it would be 1/2