Question 1155563
<br>
The given information compares Mary's and Charlie's ages to David's age.  So use David's age as the variable:<br>
x = David's age
x+16 = Mary's age  (she is 16 years older than David)
x+13 = Charlie's age  (David is 13 years younger than Charlie, so Charlie is 13 years older than David)<br>
The sum of their ages is 62:<br>
{{{(x)+(x+16)+(x+13) = 62}}}<br>
Solve using basic algebra.<br>
Then remember the question asks for Mary's age, which is x+16 -- not just x.<br>