Răspuns :
a-numarul initial
2*a-5=y
y÷5=z
z-6=5
z=6+5
z=11
y÷5=11
y=5×11
y=55
2×a-5=55
2×a=55+5
2×a=60
a=60÷2
a=30
2*a-5=y
y÷5=z
z-6=5
z=6+5
z=11
y÷5=11
y=5×11
y=55
2×a-5=55
2×a=55+5
2×a=60
a=60÷2
a=30