we need first consider what data we have available:
a = run 1.5km
b = then run 2.3km
c = walk 475m
x = a + b + c = how many km he done on treadmill
before we go anywhere, we need to unify the units, we need to change meters to fraction of kilometers, kilo meant 1000, therefore:
1km = 1000m
475m / 1000m = 0.475km
now we can substitute:
x = a + b + c = 1.5km + 2.3km + 0.475km = 4.275km
we can round that up to first decimal point and then:
4.275km = 4.3km
answer is then:
jack done on the treadmill 4.275km or rounded up 4.3km