Laneka owns a cake shop. she is currently preparing cakes for two anniversary parties. the first cake has 3 small tiers and 1 medium tiers and will serve a total of 100 guest . the second one has 3 small tiers and 2 medium tiers and will serve a total of 140 guest.. what is the system

Let r = small tier and s be medium tier.  
Then 3r + s = 100 (1) 
And 3r + 2s = 140 (2) 
Subtracting (2) from (1) we have 
 s = 40. 
 Substituting value for r into (1) we have
 3r + 40 = 100.
 3r = 100 - 40 = 60
 3r = 60
 r = 20.
 If U = 3r + s = 100 = 3r + s - 100
 Then du/dr = 3 and du/ds = 1
 Also, du/dr = 3 and du/ds = 2

All about the same size in the city the game was

Ithink it would be 160 people