Răspuns:
Explicație pas cu pas:
a) x/5 = 12/15 <=> 15·x = 5·12 => x = 5·12:15 =>
x = 60:15 => x = 4
sau : ³⁾x/5 = 12/15 => 3x = 12 => x = 4
b) 3/x = 21/35 <=> 21·x = 3·35 => x = 3·35:21 =>
x = 105:21 => x = 5
c) 15/60 = x/12 <=> 60·x = 12·15 => x = 12·15:60 =>
x = 180:60 => x = 3
d) 36/18 = 10/x <=> 36·x = 10·18 => x = 180:36 =>
x = 5