Răspuns:
a=60·[(1,2)²ˣ³:(1,2)⁴ˣ⁰:(1,2)²ˣ²-0,9]+114,6
a=60·[(1,2)⁶:1:(1,2)⁴-0,9]+114,6
a=60·[(1,2)⁶⁻⁴-0,9]+114,6
a=60·(1,2²-0,9)+114,6
a=60·(1,44-0,9)+114,6
a=60·0,54+114,6
a=32,4+114,6
a=147 nr total al ferestrelor
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notam cu a=ferestre deschise , b= ferestre inchise
a+b=147
a=b:6=>b=6a
a+6a=147
a=147:7=>a=21 ferestre deschise
b=6·21=126 ferestre inchise