Can you add variables with different exponents

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)}

The perimeter of a stage is 116 feet. it is 17 feet wide. how long is it?

If 1/√5+1/√5+1=p+q√r , find the values of p, q and r