Answer:
L= 5+2s
Explanation:
 
Let L = the larger # and S = the smaller #. 
 A large # is 5 more than twice a smaller #.....This gives Eq 1) L = 5 + 2S 
 Their sum is 80...This gives Eq 2) L + S = 80. 
 Substitute Eq 1) into Eq 2), you get 
 L + S = 80 
 5 + 2S + S = 80 
 L = 5 + 2S