hi I'm new to this website nice to meet u, I rele need help on this it rele confuses me and seems very difficult so can u help me out?

-3=2m-3n
2m+n=-15

Combine the equations so that either the m or n-terms cancel each other out. Solve for the remaining variable. You'll want to multiply each equation by certain constants so that either the m or n-terms are opposites of each other. Then plug the obtained value in to one of the original equations to solve for the other variable.

take the first equation and swap the left and right sides over. Then subtract the equations from each other and you should end up with an equation you can solve.