I need to find the set up for this problem:

an old man is asked by a young man: "what is your age"? He responds I am 3 times older than you when I was your age. When you will be my age the sum of our ages will be 100.

can anybody help me? I only need the set up(linear equation)

I need help... 6(x-7)- 7 (x-6) = x+6 - (x-4)

i need help.... 6(x-7)- 7 (x-6) = x+6 - (x-4)

Please start your own thread.