Joan, Kylie, Lillian, and Miriam all celebrate their birthdays today. Joan is 2 years younger than Kylie, Kylie is 3 years older than Lillian, and Miriam is one year older than Joan. Which of the following could be the combined age of all four women today?
How can we attack this problem (4 variables/3 equations) without backsolving
We don't need to solve for the 4 variables coz the question asks "which...could
Let a, b, c and d be the ages of J, K, L and M respectively.
b-3=c ---> c= a-1
d-1= a ---> d= a+1
---> the combined age= a+b+c+d= a+ (a+2) + (a-1)+ ( a+1)= 4a+2----> the correct answer must be one which is divided by 4 has remainder of 2. Only 54 satisfies ---> D it is.