Criminal law — Driving under influence — Evidence — Breath test — Independent blood test — Reasonable assistance — Officer’s mention of prior instance in which another person obtained blood test that revealed higher alcohol level than was measured by breath test was not so egregious as to hinder defendant’s decision on whether to obtain blood test where officer also correctly informed defendant that he would have to pay for independent test and that officer would provide him with a list of numbers to call — Denial of motion to suppress is affirmed