Răspuns:
Explicație pas cu pas:
5•{6:[7•(a+2)-15)+1}-5=5
5•{6:[7•(a+2)-15)+1} = 5 + 5 = 10
6:[7•(a+2)-15)+1 = 10 : 5 = 2
6:[7•(a+2)-15] = 2 - 1 = 1
7•(a+2)-15 = 6 : 1 = 6
7•(a+2) = 15 + 6 = 21
a + 2 = 21 : 7 = 3
a = 3 - 2 = 1
__________________
Verificare
5•{6:[7•(1+2)-15)+1}-5=5
5•[6:(7•3-15)+1]-5=5
5•[6:(21-15)+1]-5=5
5•(6:6+1)-5=5
5•(1+1)-5=5
5•2-5=5
10 - 5 = 5
5 = 5 adevarat, deci a = 1 este solutia corecta