How far will a linear spring with a constant of 630 N/m be stretched by a 140 N force?
spring constant: k = 630 N/m
force: F = 140 N
Starting formula 

Algebra: divide both sides by k 

Algebra: k's cancel on right 

Algebra: switch left and right 

Plug in numbers with units 

Divide: 630/140 = 4.5 

Final result with significant figures and unit 