Form the pair of linear equations in the following problems, and find their solutions graphically. : 10 students of Class X took part in a Mathematics quiz. If the number of girls is 4 more than the number of boys, find the number of boys and girls who took part in the quiz.

Form the pair of linear equations in the following problems and find their solution by substitution method : A horse and 2 cows together cost ? 680. If a horse costs ? 80 more than a cow, find the cost of each.

Form the pair of linear equations in the following problems, and find their solutions graphically : 5 pencils and 7 pens together cost Rs 50 whereas 7 pencils and 5 pens together cost Rs 46. find the cost of one pencil and that of one pen.

Form the pair of linear equations in the following problems and find their solution by substitution method : Anu has only 10 paise and 50 paise coins in her purse. If the total number of coinsis 17 and their total value is ? 4.50, find the number of each type of coins.

From the pair of linear equations in the following problems and find their solutions (if they exist) by elimination method : There are rs 2 and rs 5 coins in a purse. If there are 60 coins of value rs 195, find the number of coins of each kind.

Form the pair of linear equations in the following problems, and find their solutions (if they exist) by the elimination method : The sum of the digits of a two-digit number is 9. Also, nine times this number is twice the number obtained by reversing the order of the number. Find the number.