J=Jesse
M=Mom
S=Son
J/M=6/11
J/S=12/1 (it can't be 1/12)
J/M=6/11=12/22 (because the ratio of Jesse to Son is 12/1)
x=the number you have to multiply the terms of the ratios by to get the ages
J/M=12x/22x
J/S=12x/1x
in 4 years...
J/M=(12x+4)/(22x+4)
J/S=(12x+4)/(x+4)
(12x+4) is Jesse's age (don't count Jesse's age twice)
(22x+4)=Mom's age
(x+4)=Son's age
the sum of their ages is 117
(12x+4)+(22x+4)+(x+4)=117
35x+12=117
35x=117-12
35x=105
x=105/35
x=3, the multiplier
12x=12*3=36 years old for Jesse
22x=22*3=66 years old for Mom
x=3 years old for Son