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SSLC Mathematics Solutions — Part -1 YK, , Exercise 3.2, , . Form the pair of linear equations in the following problems, and find their solutions, graphically., (i) 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., (ii) 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, (i) Let the number of girls be x number of boys be y, x+y=10 (a; x-y=4 (2), , dQ) x+y=10>y=10-x, x=5=>y=10-5=5, , , , x=4=>y=10-4=6, x=6=>y=10-6=4, , x [*[*]|*, y=1o-x[ = [* [4, , ()=x-y=4>y=x-4, , , , , , , , , , , , , , x=5=>y=5-4=1, x=4>y=4-4=0, x=3>y=3-4=-1, , , , , , , , x 3] 4 3, y=x-4 |1 | 0 -l, Two lines are intersecting at the point (7, 3), , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , * The solution is) x=7, y=3, , =>Number of Girs = 7, Number of boys = 3, (ii) Let the cost of a pencil be Rs x, and the cost of a penis Rs y Then the equation are:, 5x+7y=50 and 7x+5y = 46 |, , , , , , , , , , Sx+7y =50— y=, x=3>y= 50-5(3) _ 50-15 =B=5, 0 10 -50, x=105 ee as 50 - a 4) 70 _, x= d= y=-—7 == 10, 3 10 -4, ps fe] |, 7x + Sy = 46, = Sy =46-7x y= tf}, K=B ay = SO = Zl ‘ 5, 46-7(3) _ 46-21 _ 25, =3 > ys —— = = = sla | =, ie ’ 4 7(-2) Sam — 200- “4x —2 5) 12, x=-2=y aS ee =, , 5 5, , Two lines are intersecting at the point (3, 5). -. The solution is) x=3, y=5