Four friends were born in consecutive years. the sum of their ages is 94. what is the age of the oldest friend?

Hello,

We don't need algebra to solve this.

I suppose the ages are 1,2,3,4
Their sum is 1+2+3+4=10.
To obtain 94 we must add 94-10=84 for 4 persons =>84/4=21 to each

Ages are
1+21=22
2+21=23
3+21=24
4+21=25

But if really want an algebric resolution:

Let's x the age of the youngest
x+1,x+2,x+3 the others.

x+(x+1)+(x+2)+(x+3)=94
==>4x+6=94
==>4x=88
==>x=22
Ages are 22,23,24,25.

The oldest friend is 25 years old.

3x+9+4x+x=8x+9that's the answer for your question.