Question

Determinați cifra b astfel încât 7 b cu bară deasupra egal cu b b cu bară deasupra plus 20 punct​

Answer 1

 

$\displaystyle\bf\\\overline{7b}=\overline{bb}+20\\\\b+0=b\\\\b+2=7\\\\b=7-2\\\\\boxed{\bf~b=5}\\\\Verificare:\\75=55+20\\75=75~~~~corect$