A 450N box is on a frictionless surface being pulled by a 350 N weight hanging from a cord on a frictionless p

a) what is the mass and acceleration of the box?
b) what force is exerted on the cord?
please someone explain to me how to solve this! thank you

450 N = mass X acc due to gravity
450 N = mass X 10m/s^2
there fore mass = 450/10 kg
mass = 45 kg
We know.......... Force = mass X acceleration
350 N= 45 X acceleration
acceleration = 350/45 m/s^2