Răspuns:
Explicație pas cu pas:
Notam cu n - numarul la care ma gândesc
[tex]\bf [( n\cdot 3-10):5] +6\cdot 15 =100[/tex]
[tex]\bf [( n\cdot 3-10):5] +90 =100[/tex]
[tex]\bf [( n\cdot 3-10):5] =100-90[/tex]
[tex]\bf ( n\cdot 3-10):5 =10~~\bigg|\cdot5[/tex]
[tex]\bf n\cdot 3-10 =50[/tex]
[tex]\bf n\cdot 3 =50+10[/tex]
[tex]\bf n\cdot 3 =60~~~\bigg|:3[/tex]
[tex]\red{\bf \underline{ n=20}}[/tex]
Răspuns:
[(a×3-10):5]+6×15=100
[(3a-10):5]+90=100
(3a-10):5=100-90
3a-10=10×5
3a=50+10
a=60:3
a=20