If 4 biro and 5 pencils cost \(\$ 100\), while twelve biro and ten pencils cost \(A 240\), find the cost of biro and pencil?
A. N18.00 B. N12.00 C. N240 D. N22.00
Correct Answer: C
Explanation
Let \(B =\) Biro and \(P =\) Pencil \(4 B +5 P =100 \ldots(1)\) \(12 B +10 P =240\) \(12 B +10 P =240 \ldots(2)\) \(6 B +5 P =120 \ldots(3)\) Subtract eqn (1) from (3) \(2 B =20, B =\frac{20}{2}=10\) Put \(B =10\) into eqn (1) \(4(10)+5 P=100\) \(40+5 P =100\) \(5 P =100-60\) \(5 P =40, P =\frac{40}{5}=8\) Therefore \(P = N 8.00\) and \(B = N 10.00\)
