100 acres = 40 acres by h + 60 acres by h+k

h' rate = 40/8= 5acres/hr

h+r = 60/5 = 12 acres/hr

r= 12-5= 7acres/hr

hi i also did the same but can u exlplain d steps

100 in total = 40 acres by h first + 60 acres by h+k afterwards

now we know, h does 40 acres in 8 hrs.Means per hour h does -

h' rate = 40/8= 5 acres/hr

also, h+k does 60 acres in 5 hrs means per hour they do =
h+r = 60/5 = 12 acres/hr

h+r = 12 acres per hour. out of which in 1 hr h does 5 acres. Thus r will do -
r= 12-5= 7acres/hr

I hope this helps.