Question 252124
let the no. of sheep be s
and no. of goats be g

so we have s+g=24  -------------- 1

also if he had sold the whole herd at the uniform price of $120 per animal
he would have earned 24*120=2880$
this 2880$ is 360 more than what he actually earned
so he earned 2880-360 = 2520$

i.e., 140*s + 100*g = 2520 ----------2

from equations 1 & 2    

40s = 2520-2400 = 120

so    s = 3 
and   g = 21

thus the no. of goats he sold = 21 Ans