Question

Suma a trei numere este de 210 sa se afle numerele stiind ca primul numar reprezinta 75% din al doilea iar al treilea numar este egal cu suma celorlalte doua

Answer 1

$a,b,c-nr.$

$a + b + c = 210$

$a = \frac{75}{100} \times b = \frac{3}{4} \times b = \frac{3b}{4}$

$c = a + b = \frac{3b}{4} + b = \frac{3b}{4} + \frac{4b}{4} = \frac{7b}{4}$

$\frac{3b}{4} + b + \frac{7b}{4} = 210$

$\frac{7b}{4} + \frac{7b}{4} = 210$

$\frac{14b}{4} = 210$

$\frac{7b}{2} = 210$

$7b = 2 \times 210$

$7b = 420$

$b = \frac{420}{7}$

$b = 60$

$a = \frac{3b}{4} = \frac{3 \times 60}{4} = \frac{3 \times 30}{2} = 3 \times 15 = 45$

$c = \frac{7b}{4} = \frac{7 \times 60}{4} = \frac{7 \times 30}{2} = 7 \times 15 = 105$