Given that m varies directly as n then
m = kn where k is the constant of proportionality. if m = 11.6 and n = -2.4 then
11.6 = k * -2.4
k = 11.6/-2.4
k = -29/6
Hence m = -29n/6
If n = 22.5 then
m = -29 * 22.5/6
m = -108.75
when m = -29
-29 = -29n / 6
n = 6
Hence when n = 22.5, m = -108.75
when m = -29 , n = 6