Answer: 
Equilvant equations have the same solutions 
For example, the two equalivanent equations are 
2x = 10 
x = 5 
The above equations are equilvaent because if we solve the first equation for x, we get the second. 
2x = 10 
dividing both sides by 2 gives 
2x/2 = 10/ 2
x = 5