Mr. Spears was purchasing supplies for his math classroom. He had $25 to spend. Mechanical pencils and erasers come in bundles of 10. Each eraser costs $0.50. Fill in the missing place in the equation to compute the cost of each mechanical pencil.

Answer 1

Since each eraser costs $0.50 and there are 10 erasers in a bundle, the cost of a bundle of erasers is $0.50 x 10 = $5.
Mr. Spears has $25 to spend, and the cost of the erasers is $5, so $25 - $5 = $<<25-5=20>>20 must be the cost of the mechanical pencils.
Since the mechanical pencils and erasers both come in bundles of 10, each $20 purchase must contain 20/10 = <<20/10=2>>2 bundles.
Therefore, the cost of each mechanical pencil is $20/2 = $<<20/2=10>>10. Answer: \boxed{10}.