100-[25+5×(a-b):7]=5
ca sa imi fie mai usor notez paranteza (a-b) cu t. deci voi avea
100-(25+5×t:7)=5
25+5×t:7=100-5
25+5×t:7=95
5×t:7=95-25
5×t:7=70
5×t=70×7
5×t=490
t=490:5
t=98
daca t=98 si (a-b)=t=> a-b=98=>a=98+b
acum a+b=75+(2000-85×12):4 il inlocuiesc pe a in ecuatie (nu uita am aflat mai sus ca a=98+b!!)
98+b+b=75+(2000-85x12):4
98+2b=75+(2000-1020):4
98+2b=75+980:4
98+2b=75+245
98+2b=320
2b=320-98
2b=222
b=222:2
b=111
a=98+b=>a=98+111=>a=209
verificam
a+b=75+(2000-85×12):4?
209+111=75+(2000-1020):4?
320= 75+980:4?
320=75+245?
320=320 (adevarat)
100-[25+5×(a-b):7]=5 ?
100-[25+5x(209-111):7]=5?
100-(25+5x98:7)=5?
100-(25+490:7)=5?
100-(25+70)=5?
100-95=5?
5=5 (adevarat)
