S=b1/(1-q)
q=b2/b1
q=1/5
S=(4/5)/(1-1/5)
S=(4/5)/(4/5)
S=1
х+5у=35,3х+2у=27
x=35-5y
3(35-5y)+2y=27
-15y+2y=27-105
-13y=-78
y=6
x=35-5*6=35-30=5
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