Calculating Combined Disability
If you have more than one disability rating from the VA use this calculator to determine the combined rating. VA math is different than you would expect. A 30% rating and a 60% rating would be 72% rounded down to 70%.
This calculator uses a formula derived from title 38CFR4.25 USC.

Corporal Atchley (Long Beach, CA), a squad leader of Company B, 1st Battalion, 9th Marines, guards a Viet Cong