Question 113067
:
Let G = G.W. age in  1750
Let T = T.J. age in  1750
:
George Washington was born eleven years before Thomas Jefferson. 
T = G - 11
:
In 1770 Washington's age was three years more than seven times the age of Jefferson in 1748.
:
G + 20 = 7(T - 2) + 3
G + 20 = 7T - 14 + 3
G + 20 = 7T - 11
G = 7T - 11 - 20
G = 7T - 31
:
How old was each man in 1750?
:
Substitute (G-11) for T:
G = 7(G-11) - 31
G = 7G - 77 - 31
G = 7G - 108
G - 7G = - 108
-6G = -108
G = -108/-6
G = +18 yrs old G in 1750
Then 
T = 7 yrs old in 1750
:
I checked out the actual dates of birth and it checks out:
 G.W. born in 1732 and T.J was both in 1743