Question

An object on a spring vibrates in a simple harmonic motion with afrequency of 1.0 Hz and an amplitude of 5.00 cm. If a timer isstarted when the mass is in the equilibrium position, what is theobject's distance from its equilibrium position at t=2.25 s?
A) 7.50 cm B) 5.00 cm C) 2.50 cm D)1.25 cm E)zero

i dont remember anywhere in this chapter giving an equation withtime and distance so im stuck on what equation to use to figurethis out. Help please and thank you