Write two addition equations that each have a sum of -21.5

Anyone know? will mark brainliest if correct!

Someone this asap for a group of students attends a basketball game. * the group buys x hot dogs at the concession stand for $2 each. * the group buys y drinks at the concession stand for $3 each. the group buys 29 items at the concession stand for a total of $70. how many hot dogs did the group buy?

Asystem of equations has 1 solution.if 4x-y=5 is one of the equations , which could be the other equation ?