Question 181010
Lara is twice as old as Jonathan.  Jonathan is 6 years younger that Tasha. Tasha is 12 years younger than Lara.  How old is each? 
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L = 2J
J = T-6
L = T+12
Sub for L into the 3rd eqn
2J = T+12
Then sub for J.
2(T-6) = T+12
2T-12 = T+12
T = 24

J = 18
L = 36