Răspuns:
Explicație pas cu pas:
1.
6 - 3 = 3
2.
480*20/100 = 96
3.
a = 7b/5
3a - 2b = 21b/5 - 10b/5 = 11b/5
a + b = 7b/5 + 5b/5 = 12b/5
(3a - 2b)/(a + b) = 11b/5 : 12b/5 = 11b/5 *5/12b = 11/12
4.
a/b = 5/7
a + b = 60
a = 5b/7
5b/7 + b = 60
5b/7 + 7b/7 = 60
12b/7 = 60
b = 7*60/12 = 35
a = 60 - b = 60 - 35 = 25
a*b = 25*35 = 875
5.
5x - 9 = 6
5x = 9 + 6 = 15
x = 15 : 5 = 3
6.
A = {270. 272, 274, 276, 278}
B = {120, 123, 126, 129}
A U B = {120, 123, 126, 129, 270. 272, 274, 276, 278}
card (A U B) = 9
7.
a/4 = b/5 = c/6 = k
a = 4k
b = 5k
c = 6k
a + b + c = 180°
4k + 5k + 6k = 180°
15k = 180°
k = 180° : 15 = 12°
a = 4*12° = 48°
b = 5*12° = 60°
c = 6*12° = 72°
8.
38°33' + 6°41' - 20°49' = 44°74' - 20°49' = 24°25'
9.
(60° + 108°)/2 = 168°/2 = 84°
__________
1.
7/3 + [(3/2 + 4/9 * 9/4) : 1/9 + 11/4] : 1/4
= 7/3 + [(3/2 + 1) : 1/9 + 11/4] : 1/4
= 7/3 + (5/2 *9 + 11/4) : 1/4
= 7/3 + (45/2 + 11/4) *4
= 7/3 + (90/4 + 11/4)*4
= 7/3 + 101/4 *4
= 7/3 + 101
= 7/3 + 303/3
= 310/3
2.
a = numarul apartamentelor cu 2 camere
b = numarul apartamentelor cu 3 camere
a + b = 28
2a + 3b = 76
a = 28 - b
2(28 - b) + 3b = 76
56 - 2b + 3b = 76
b = 76 - 56 = 20
a = 28 - 20 = 8
