48) In an alloy of 80 gram copper is 60 gram. The remaining is zinc. The ratio off copper to zinc is

49) A man spends 15% of his income on agriculture, 21% on family and 24% on education of children. If he saves Rs 360, find out the total income.

50) If (y+2)(y-3)=(y-6)(y+9)+8, find the value of y.

51) Find the area of equilateral triangle, if its side is 10 cm.

52) A hollow shaft has 375 mm outside diameter and 275 mm inside diameter. The area of cross section is equal to