点線(てんせん)dotted line, perforated line

この線(せん)は点線(てんせん)ではなくて実線(じっせん)だ。

This line is not a dotted line, but a solid line. {dotted line, perforated line}

点線(てんせん)の点(てん)と点(てん)の間(あいだ)は一(いち)ミリ程(ほど)あいている。

The space between the dots on the dotted line is about one millimeter. {dotted line, perforated line}

多(おお)くの点(てん)を連(つら)ねてつくった線(せん)を点線(てんせん)と言(い)います。

A line made by connecting many points is called a dotted line. {dotted line, perforated line}

この点線(てんせん)の部分(ぶぶん)でクーポンを切(き)り離(はな)すことが出来(でき)るそうです。

It seems that you can detach the coupon at this dotted line section. {dotted line, perforated line}

問題(もんだい)：「点線(てんせん)の長方形(ちょうほうけい)と実践(じっせん)の長方形(ちょうほうけい)が重(かさ)なる部分(ぶぶん)の面積(めんせき)を求(もと)めなさい。」

Question: "Find the area of the part where the rectangle with a dotted line overlaps with the rectangle with a solid line." {dotted line, perforated line}