Question

Ex 3 4 de la amandoua fise varog frumos dau coroana

Answer 1

Răspuns:

F1

3.

a=17b/5

17b/5 - b = 72

17b - 5b = 360

12b = 360

b=30

a=102

4.

x=2y/3

2y/3 + y = 225

2y+3y=675

5y=675

y=135

x=90

F2

3.

x=19y/6

19y/6 - y = 91

19y - 6y = 546

13y=546

y=42

x=133

4.

a=3b/7

3b/7 + b = 320

3b+7b=320•7

10b=320•7

b=224

a=96

Answer 2

Explicație pas cu pas:

Vom folosi proprietatile proportiilor.

1.

3)

a-b = 72

a/17 = b/5 ⇔ a/b = 17/5 ⇔ a/(a-b) = 17/(17-5) ⇔ a/72 =17/12 ⇔ a/6 =17 ⇒

a = 6 x 17 = 102 ⇒(din prima relatie)

b=a-72=102-72=30

4.

x+y=225

x/y=2/3 ⇔ x/(x+y) = 2/(2+3) ⇔ x/225 = 2/5 ⇔ x/45 = 2 ⇒

x = 90 ⇒

y =225-90 = 135

2.

3)

x-y=91

x/19=y/6 ⇔ x/y = 19/6 ⇔ (x-y)/y = (19-6)/6 ⇔ 91/y = 13/6 ⇔ 7/y = 1/6 ⇒

y = 7*6 = 42 ⇒

x = 91 + 42 = 133

4)

a+b = 320

a/b = 3/7 ⇔ a/(a+b) = 3/(3+7) ⇔ a/320 = 3/10 ⇔ a/32 = 3 ⇒

a = 32 x 3 = 96 ⇒

b = 320 -96 = 224.