Please help taking a test and can’t figure it out!!!

Isee the amount was $90.00 then reduced to $75.00 , what is the percent ?

What set does not contain -3 the set of all real numbers the set of all integers the set of all whole numbers the set of all rational numbers

John used linear combination to solve the system of equations shown. he did so by multiplying the first equation by -3 and the second equation by another number to eliminate the x-terms. what number did jonas multiply the second equation by? 4x-6y=23x+5y=11