What is the simplified form of square root of 400 to the 100th power ?

What is an equation of the line that passes through the point (-2,3) and is parallel to the line whose equations is y=3/2x-4? i am stuck between y=3/2x or y=3/2x+6 : (

Write an equation of the line that passes through 9,2 and is parallel to the line y=5/3x+9

Find the percent error of the measurement 4 cm