Răspuns:
Explicație pas cu pas:
Metoda figurativa
a ____
b ____ ____
c ____ ____ ____ ____
d ____ ____ ____
10 segmente = 100
1 segment = 100 : 10 = 10
a = 10
b = 2 x 10 = 20
c = 4 x 10 = 40
d = 3 x 10 = 30
________________
Algebric
a
b = 2a
c = 2b = 2*2a = 4a
d = a + b = a + 2a = 3a
a + b + c + d = 100
a + 2a + 4a + 3a = 100
10a = 100
a = 100 : 10 = 10
b = 2*10 = 20
c = 4*10 = 40
d = 3*10 = 30