Question

aflati doua numere stiind ca suma lor este 72 si ca sunt direct proportionale cu numerele a)3 si 5 b) 2 si 7 c) 4 si 8 d) 5 si 13 e)8,4 si 15,6
DAU COROANAAA!!

Answer 1

a + b = 72

a)
{a,b}
{3,5}
a = 3k
b = 5k
3k + 5k = 72
8k = 72
k = 72 : 8
k = 9

a = 3k = 3 · 9 = 27
b = 5k = 5 · 9 = 45

b)
{a,b}
{2,7}
a = 2k
b = 7k
2k + 7k = 72
9k = 72
k = 72 : 9
k = 8
a = 2k = 2·8 = 16
b = 7k = 7·8 = 56
c)
{a,b}
{4,8}
a = 4k
b = 8k
4k + 8k = 72 
12k = 72 
k = 72 : 12
k = 6
a = 4k = 4·6 = 24
b = 8k = 8·6 = 48
d)
{a,b}
{5,13}
a = 5k 
b = 13k
5k + 13k = 72
18k = 72 
k = 72 : 18
k = 4
a = 5k = 5·4 = 20
b = 13k = 13·4 = 52
e)
{a,b}
{8,4;15,6} 
a = 8,4k
b = 15,6k
8,4k + 15,6k = 72
24k = 72
k = 72 : 24
k = 3
a = 8.4k = 8.4 · 3 = 25,2 
b = 15.6k = 15.6 · 3 = 46.8