Răspuns :
[(100+x)÷75-1]×35=875
(100+x)÷75-1)=875:35
(100+x):75-1=25
(100+x):75=25+1
(100+x):75=26
100+x=26×75
100+x=1950
x=1950-100
x=1850
Probă :
[(100+1850)÷75-1)]×35=
=(1950:75-1)×35=
=(26-1)×35=
=25×35=
=875 (adevarat )
(100+x)÷75-1)=875:35
(100+x):75-1=25
(100+x):75=25+1
(100+x):75=26
100+x=26×75
100+x=1950
x=1950-100
x=1850
Probă :
[(100+1850)÷75-1)]×35=
=(1950:75-1)×35=
=(26-1)×35=
=25×35=
=875 (adevarat )
[ ( 100 + x ) : 75 - 1 ] × 35 = 875
( 100 + x ) : 75 - 1 = 875 : 35
( 100 + x ) : 75 - 1 = 25
( 100 + x ) : 75 = 25 + 1
( 100 + x ) : 75 = 26
100 + x = 26 × 75
100 + x = 1 950
x = 1950 - 100
x = 1 850 → numarul, aflat prin metoda mersului invers