What is the difference in height of Mount St. Helens before and after the eruption, expressed in meters

2950 subtracted by 2550 equals 400 you subtract

2950

-

2550

so subtract the 0's which equals 0

the subtract the 2nd furthest numbers (5-5) = 0

then subtract the next (9-5) = 4

then 2-2 = 0

so 400