6.
d) 60/40 = 9/n
60 × n = 40 × 9
60 × n = 360
n = 360:60
n = 6
e) n/3 = 48/n
n^2 = 3 × 48
n^2 = 144
n = 12
f) 4/(n+1) = 24/30
24(n+1) = 4 × 30 | : 4
6 ×n + 6 = 30
6×n = 24 | : 6
n = 4
2.
Doua fractii echivalente sunt doua fractii egale :
a) 1/2 = n/4
n = 4 /2
n = 2
b) 6/n = 18/15
6/n = 6/5
n = 5×6/6
n = 5
c) (n + 1)/22 = 2n/40
40(n+1) = 2n × 22
40n + 40 = 44n
44n - 40n = 40
4n = 40 | : 4
n = 10
