maths question for homework

Question

Mrs Charles ordered 150 pencils and 225 pens for the academy store. The pens cost 15 cents more than the pencils. Mrs Charles’ total order was $135. Mrs. Charles was quite surprised by this amount as she thought the total would be $120.

If the cost of one pencil and one pen is 69 cents, who do you think is right, the supplier or Mrs Charles? Support your answer with mathematical evidence.

What is the cost of each pencil? Each pen? Support your answer with mathematical evidence.

Answer 1

x Pencils + x +15 Pens = .69

solve for x. X = 27, so pens cost .42

150 (.27) + 225 (.42) =

40.5 + 94.5 = 135, so the supplier was correct.