Are these very technically correct with the suspended hyphens? Thank you. a five- to ten-thousand-dollar-a-year investment a ten- to twenty-percent-a-year increase a five- to ten-minute waiting period a twenty-five- to thirty-five-dollar-a-month service fee a twenty- to thirty-year mortgage Thank you.
My advice is to get a copy of the Chicago Manual of Style. They have most of the answers you're looking for. I only say this because you're asking the same questions over and over again. And yes, those look correct.
a five- to ten-thousand-dollar per year investment (or you might use 'annual' instead of the italicized words) s/a correct s/a (per month doesn't need hyphens) s/a