Răspuns :
Ma = ( a + b + c + d ) : 4
7,5 = ( a + b + c + d ) : 4
a + a + 1 + a + 2 + a + 3 = 7,5 × 4
a + a + 1 + a + 2 + a + 3 = 30
4a = 30 - ( 1 + 2 + 3 )
4a = 30 - 6
4a = 24
a = 24 : 4
a = 6
b = 7
c = 8
d = 9
7,5 = ( a + b + c + d ) : 4
a + a + 1 + a + 2 + a + 3 = 7,5 × 4
a + a + 1 + a + 2 + a + 3 = 30
4a = 30 - ( 1 + 2 + 3 )
4a = 30 - 6
4a = 24
a = 24 : 4
a = 6
b = 7
c = 8
d = 9