Question 827937
a grandfather's age is equal to the digits of his two grandchildren.
 And his age plus their ages equals 83.
 How old is he? \:
Let a = the 1st digit of grandpa's age & the age of one of the grandchildren
Let b = the 2nd digit of grandpa's age & the age of the other grandchild
then
10a + b = grandpa's age
" his age plus their ages equals 83." therefore:
10a + b + a + b = 83
11a + 2b = 83
2b = -11a + 83
b = {{{(-11a+83)/2}}}
We know that a has to be a single digit, 7,  6 would make b too much
Lets try a = 7
b = {{{(-11(7)+83)/2}}}
b = {{{6/2}}}
b = 3
Grandpa is 73, grand-kids are 7 and 3