The only way you can get from Yosemite, down the eastern side of the Sierras is Tioga pass. It is Hwy 120.
It is a steep downgrade with curves. You can do this easy. Lower gear is your friend.
This highway comes out near the eastern Sierra town of Lee Vining at Hwy 395.
Turn right, or south, on Hwy 395 for several miles and just after (south of) the June Lake junction turnoff, (Hwy 158) turn left, or east, on the now continuing Hwy 120.
This will take you to Tonopah NV. Then just follow Hwy 95 south all the way into Las Vegas.
Avoids the heat of Death Valley completely.