How do I solve for these?On a line,If M is the midpoint of segment AB, AM=4x and AB=7x+9. What is the value of MB?

I cannot figure this one out either:If B is between A and C, AB=5y+4, BC=7y-3, and AC=20y-7. Find the value of y, AB, BC, and AC.
Can someone please help me??

How do I solve for these?On a line,If M is the midpoint of segment AB, AM=4x and AB=7x+9. What is the value of MB?

If AM = 4x and AB = 7x + 9 then MB = AB - AM or 7x + 9 - 4x = ?

I cannot figure this one out either:If B is between A and C, AB=5y+4, BC=7y-3, and AC=20y-7. Find the value of y, AB, BC, and AC.
Can someone please help me??

AB + BC = AC. Substitute and solve for y, AB, BC and AC.