Question

determinati nr a si b stiind ca suma lor este 431 iar 2 xa+5xb egal 1696

Answer 1

a+b = 431 => a= 431-b 
2*a + 5*b = 1696
2*(431-b) + 5*b = 1696 => 862 - 2*b +5*b= 1696 => 3*b = 1696 - 862 => 3*b = 834 => b = 834/3 => b= 278 => a = 431-278 => a= 153

Answer 2

a+b=431
2 x a + 5 x b = 1696
a=431-b
2 x (431 - b ) + 5 x b = 1696
862 - 2 x b + 5 x b = 1696
862 +3 x b = 1696
3 x b = 1696 - 862
3 x b = 834
b = 834 : 3
b = 278
a = 431 - b
a = 431 - 278
a = 153
Proba
2 x a + 5 x b = 1696
2 x 153 + 5 x 278 = 306+1390 = 1696