How do you calculate this?

Given: x + y = 6. if xe (-15, -6, -1), then which of the following sets of ordered pairs are solutions? © {(-15, -21), (-6, -12), (-1, -7)} [(-15, 21), (-6, , 7)} {(-15, 21), (-6, 12), (-1, -7)}

Which letters from the table represent like terms? a and b b and c a and d b and d

The figure below shows rectangle abcd and the triangle eca on a coordinate plane.which of the following expressions represents the perimeter of triangle of triangle eca in units