Question

1. Calculati : 1325 - 9 x [ 280 - 3 x ( 108 -96 : 6 ) ] : 12 =



2. Daca a + b = 42 si b - 2 x c = 56 , calculati 2 x a + 5 x b + 6 x c


3. Sase muncitori termina o lucrare in 15 zile . In cate zile termina aceeasi lucrare 10 muncitori ?

Answer 1

1. 1325- 9  x [ 280-3x(108-16)] :12=
=1325- 9  x ( 280-3 x 92 ) :12=
=1325- 9  x ( 280- 276) :12=
=1325- 9 x4 :12=
=1325- 36:12=
=1325-3=
1322

2. a+b=42 /*2⇒2a+2b=84
b+2c=56 /*3⇒ 3b+6c=168
2a+5b+6c = 2a+2b+3b+6b= 84+168= 252

3.       6 muncitori....15 zile
         10 muncitori...x zile
sunt invers proportionale
6/10=x/15
x=6*15:10=90:10=9 zile