Question

Daca 5x/6y=0,3125,calculati valoarea raportului 19x-7y/5x+3y
Stiind ca 2x/9y=0,2(7),calculati valoarea raportului 8x+5y/9x-5y
Difereanta a doua numere este 438.Aflati aceste numere stiind ca 2,25%din primul numar este egal cu 8,(3) % din al doilea

Answer 1

5x/6y=3125/10000
5x/6y=5/16
x/y=6*5/16*5=6/16=3/8=k
x=3k si y=8k
19*3k-7*8k/5*3k+3*8k= 57k-56k/15k+24k= 1 k/39k=1/39

2x/9y=25/90=5/18 ⇒ x/y=5*9/18*2=5/4=k
x=5k si y=4k
8*5k+5*4k / 9*5k-5*4k= 40k+20k/45k-20k = 60k/25k=60/25=12/5

a-b=438
2,25a/100 = 75/9 * 1/100 * b
2,25a/100= 75b/ 900
2,25a=75b/9
225a/100= 25b/3
9a/4=25b/3
9a*3=25b*4
27a=100b
a/b=100/27=k
a=100k
b=27k
100k-27k=438
73k=438
k=438:73=6
a=100*6=600
b=27*6=162