If lorenzo buys 3 shirts for s dollars and 2 pairs of pants for p dollars a pair. what does the expression 3s+2p represent

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)}

Anyone know? will mark brainliest if correct

What is the missing step in this proof ?