Answer:
45 km/hr
Explanation:
total distance = 90
Increased speed = x+15
90/x - 90/x+15=1/2
90(1/x - 1/x+15)=1/2
90(x+15-x/x^2+15x)=1/2
equation is:
x^2+15x-2700=0
x^2+60x-45x-2700=0
x(x+60)-45(x+60)=0
(x+60)(x-45)=0
x= -60, x=45
reject the negative value = -60
usual speed=45 km/ hr
Answer:
Ancient civilizations based a large part of their economy and their subsistence on trade and exchange of goods. Thus, they were guided by a very simple premise: they traded what they had left over, to obtain in exchange what they lacked. For example, if a civilization overproduced wheat, it could trade that surplus for goods it did not have, such as animals. In this way, all civilizations covered their needs without the obligation to procure them all by their own hand.
