Odpowiedź:
a) 5/3 = a/2
10/6 = 3a/6 /*6
10 = 3a / :3
a = 10/3
a = 3 1/3
b) 3/10 = x/4
12/40 = 10x/40 / *40
12 = 10x / :10
x = 12/10
x = 1,2
c) 3/x = 7/ x + 5
( mnożymy na krzyż)
3(x + 5) = 7x
3x + 15 = 7x
15 = 7x - 3x
15 = 4x / :4
x = 15/4
x = 3 3/4 = 3,75
d) a +3 / 5 = 7/5
5(a + 3) = 35
5a + 15 = 35
5a = 35 - 15
5a = 20 / :5
a = 4
