Answer: there were 190 children, 140 parents, and 70 grandparents in attendance at the family reunion.
Step-by-step explanation: Let's denote the number of children, parents, and grandparents as "c", "p", and "g", respectively.
We are given three pieces of information:
The total number of people in attendance is 400:
c + p + g = 400
There were twice as many parents as grandparents:
p = 2g
There were 50 more children than parents:
c = p + 50
We can use this system of equations to solve for the unknown variables.
First, we can use equation (2) to express "p" in terms of "g":
p = 2g
Next, we can substitute this expression for "p" into equation (3) to get:
c = 2g + 50
Now, we can use equations (1) and (4) to eliminate "p" and "c" from the system and express "g" in terms of only known quantities:
c + p + g = 400
2g + 50 + p + g = 400 (substituting c=2g+50)
3g + p = 350 (simplifying)
We can then substitute the expression for "p" from equation (2) into this last equation to obtain:
3g + 2g = 350
Simplifying:
5g = 350
Solving for "g", we get:
g = 70
Now, we can use equation (2) to find "p":
p = 2g = 2(70) = 140
Finally, we can use equation (3) to find "c":
c = 2g + 50 = 2(70) + 50 = 190
Therefore, there were 190 children, 140 parents, and 70 grandparents in attendance at the family reunion.