Question

Coroana. Va rog frumos. ​

Answer 1

Răspuns:

Explicație pas cu pas:

17.

Numere de doua cifre sunt 10, 11,......, 98, 99, adica 90 de numere

a) 19, 29, 39, 49, 59, 69, 79, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99 = 18 numere

(18/90)*100 = 20%

b) 12, 15, 18, 24, 27, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 63, 66, 69, 72, 75, 78, 81, 84, 87, 90, 93, 96, 99 = 29 numere

(29/90)*100 = 32,(2)%

c) 10, 11, 12, 13, ...., 23, 24 = 15 numere

(15/90)*100 = 16,(6)%

d) 15, 25, 35, 45, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 65, 75, 85, 95 = 18 numere

(18/90)*100 = 20%

________

18.

a) 5a/100 = 8b/100

5a = 8b

a/b = 8/5

b) 12a/100 = 20b/100

12a = 20b

a/b = 20/12 = 5/3

c) 7a/100 = 11b/100

7a = 11b

a/b = 11/7

d) 15a/100 = 25b/100

15a = 25b

a/b = 25/15 = 5/3

19.

40a/100 = b

40*b/100 = (40*40a/100)/100 = 16a/100 = 16% din a

20.

A = 20x/100

B = 30x/100

A/B = (20x/100) : (30x/100) = 20x/100*100/30x = 2/3