The deceleration formulas calculate the rate of decrease in overall speed. The equation is s ut 12at2 where s - distance u - inititial velocity and a - acceleration. The other formula if you have the initial and final speed add the two together and divide by 2.
What was the initial velocity.
Vx would be Vsin angle Vy would be Vcos angle then use the equation Vfinal Vyinitial gt. The initial velocity is formulated as. V 1 - v 0 a. V 0 a t.