Răspunsuri

2014-08-19T23:39:34+03:00
B/a=5/7

b/5=a/7=k
b=5k
a=7k

a-b=42
7k-5k=42
2k=42
k=21

a=7*21= 147
b=5*21=105
2014-08-19T23:45:27+03:00
X/y = 7/5
x-y = 42 . 

x = 42+ y 
⇒ 42+y/y = 7/5
⇒5(42+y) = 7y 
210 + 5y = 7y 
210 = 7y-5y
210=2y
y=210:2
y=105 

x =105+ 42
x=147.