Question

If $205+115=A$ and $79+69+2=B,$ then find the values of $A$ and $B.$

• A. $A=320,B=150$
• B. $A=320,B=160$
• C. $A=320,B=162$
• D. $A=310,B=162$

Answer 1

The correct option is A $A=320,B=150$

$205+115=200+5+100+15=\underset{–}{200+100}+\underset{–}{5+15}=\underset{–}{300+20}=320$

$\because 205+115=A,$ we have $A=320.$

$79+69+2=(70+9)+(60+9)+(1+1)=(70+60)+(9+1)+(9+1)=70+60+10+10=\underset{–}{70+30}+\underset{–}{30+10+10}=\underset{–}{100+50}=150$

$\because 79+69+2=B,$ we have $B=150.$

$\therefore A=320,B=150$