Explanation:
[tex]a = \frac{change \: in \: velocity}{change \: in \: time} [/tex]
[tex]a = \frac{v - u}{t} [/tex]
[tex]v = 7 {ms}^{ - 1} [/tex]
[tex]u = 15 {ms}^{ - 1} [/tex]
[tex]t = 3 \: seconds[/tex]
[tex]a = \frac{7 - 15}{3} [/tex]
[tex]a = \frac{ - 8}{3} [/tex]
[tex]a = - 2.67 \: {ms}^{ - 2} [/tex]
