Let cost of 1 pen = ₹x and cost of 1 pencil = ₹y
Rita bought 9 pens and 7 pencils for ₹66:
9x+7y=66 ... (1)
Megha bought 5 pens and 11 pencils for ₹58:
5x+11y=58 ... (2)
Multiply equation (1) by 5:
45x+35y=330 ... (3)
Multiply equation (2) by 9:
45x+99y=522 ... (4)
Subtract equation (3) from equation (4):
45x+99y=522
45x+35y=330
64y=192
y=64192
y=3
Cost of 1 pencil = ₹3
Cost of 3 pencils = 3×3
Cost of 3 pencils = ₹9