Select all the systems of equations that have exactly one solution. y = 3x + 1, y = -3x + 7
y = 3x + 1, y = x + 1
y = 3x + 1, y = 3x + 7
x + y = 10, 2x + 2y = 20
x+ y = 10, x + y = 12

You are responsible for designing a new city. you are inspired by pierre charles l'enfant, who laid out the streets of our nation's capital. numbered streets run north and south, and lettered streets run east and west. avenues are named after states, and they intersect the streets on a diagonal. the streets are parallel and the intersections form similar triangles. 18th st. is 454 meters long and the intersection of 18th and k st. is 207 meters from connecticut ave. if 19th st. and k st. is 385 meters from connecticut ave., what is the length of 19th st.?

Given a(-12,5) and b(12,29) find the point that divides the line segment ab three-eighths of the way from a to b

Cd is the perpendicular bisector of both xy and st, and cy=20. find xy.