when you solve an inequality the result is an interval when you solve an equation is a number or set ex x^2=25 x=-+5 the result is finite numbers
when you multimply an equation the sign inverses but when you solve an equation there is nothing to change
similiarities
you can add and subtract numbers from both sides
diving and multypling the equation or inequation by a positive numeber as i said in the beggining by multypling or dividing with a negative number the equation s sign inverses ex >= becomes <=