URGENT! What is the solution set of the following system of equations?

x + y = 0

x - y + 2 = 0

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

Asurvey of 2,000 doctors showed that an average of 3 out of 5 doctors use brand x aspirin. how many doctors use brand x aspirin

Choose the more precise measurement. 26.4 cm or 8.39 cm