Question

sa se determine doua nr.direct proportionale cu 3 si 4 a caror suma e 70

Answer 1

{a,b} d. p. {3,4}
a+b=70
a/3=b/4= k
a/3=a⇒3k
b/4=b⇒4k
3k+4k=70
7k=70
k=70/7=10
a=10x3=30
b=10x4=40

Answer 2

Notam numerele cu a si b.
(a,b) d.p. (3,4)
a supra 3 = b supra 4 = k 
a = 3k si b = 4k 
a+b=70
3k+4k=70
7k=70
k=70:7
k=10
a = 3k = 3 x 10 = 30
b= 4k = 4 x 10 = 40