What’s one way to check the answer to 5x6=30

Match the equivalent expressions. x - 3y + 12 12 - 3y - 2x + x + 2x 3x + 2y - 2x + y + 12 3y + 12 3x + y - 12 4y + 3y + 3x - 6y - 10 - 2 x + 3y + 2x - 3x + 7 + 5 x + 3y + 12 5 + 2y + 7x - 4x + 3y - 17

Solve the equation by completing the square. x^2+2x=17

The length of the line segment joining the midpoints of sides ab and bc of the parallelogram abcd is 10. find the length of diagnol ac