How many thousands equal 90 hundreds

Which of the following system of equation is not equal to the system of equations is not equal to the system of equations shown below

The transitive property of equality states that: o if a = b, then bra o if a = b, then ac = bc o if a = b and b= c, then a = if a = b and c= c, then a + b = b + c

Me because some of question i don’t understand