The sum of the age of andy and his parents is 72.In how many years time will the sum of their age be 90?
(90-72)/2 = 9
a = Andy's present age
m = Mom's present age
d = Dad's present age
m + d + a = 72
After x years:
Mom will be m + x yrs old
Dad will be d + x yrs old
Andy will be a + x yrs old
m + x + d + x + a + x = 90
m + d + a + 3 x = 90
We know:
m + d + a = 72
So:
72 + 3 x = 90 Subtract 72 to both sides
72 + 3 x - 72 = 90 - 72
3 x = 18 Divide both sides by 3
x = 18 / 3 = 6
After 6 years the sum of their age be 90.
I neglected the fact that there were two parents...
Always read the problem carefully!
To solve this problem, we can start by setting up equations based on the given information.
Let's assume Andy's current age is A, and his parents' combined age is P. The sum of their ages is given as 72, so we can write our first equation as:
A + P = 72
Now, we need to determine how many years it will take for the sum of their ages to be 90. Let's call this number of years T. In T years, Andy's age will increase by T, and his parents' combined age will increase by T as well. Therefore, we can rewrite our equation as:
A + T + P + T = 90
Simplifying the equation, we have:
A + P + 2T = 90
Since we know A + P = 72 from the first equation, we can substitute it into the second equation:
72 + 2T = 90
To solve for T, we isolate the variable:
2T = 90 - 72
2T = 18
T = 18/2
T = 9
Therefore, in 9 years' time, the sum of Andy and his parents' ages will be 90.