Explain how to find the constant of porportionality for the ratio of robins to cardinals

Which shows the image of rectangle abcd after the rotation (x, y) → (–y, x)?

Add the fractions and simplify 1/2+ 1/3

Expresa commuter train leaves downtown sation and travels at a average speed of 55 miles per hour towards the north side sation, which is 50miles away. thirty minutes later, express commuter train #7 leaves north side and travels at a average speed of 35miles per hour towards downtown sation. at the moment the two trains pass each other, how far(in miles) is train #12 from the downtown sation and how long(in minutes) has the #12 train been traveling