Let h represent the height above the ground, in metres. Let t represent time, in minutes. h = 800 - 55t and h = 80t.

If h=80t, then by substitution method: 80t= 800- 55t

Simplified to: 135t=800

\(\displaystyle\frac{{800}}{{135}}\) gives you: t=5.925

having the t value you can then put it into the "h=80t" equation as h=80(5.925), giving you: h= 474

To check mathematical accuracy, plug these answers back into the equation as 474= 800 -55(5.925) and 474= 80(5.925) Multiplying these out you would have balancing answers :)

If h=80t, then by substitution method: 80t= 800- 55t

Simplified to: 135t=800

\(\displaystyle\frac{{800}}{{135}}\) gives you: t=5.925

having the t value you can then put it into the "h=80t" equation as h=80(5.925), giving you: h= 474

To check mathematical accuracy, plug these answers back into the equation as 474= 800 -55(5.925) and 474= 80(5.925) Multiplying these out you would have balancing answers :)