# Addition of Decibels **URL:** \ **Category:** Project Planning & Design\ **Created:** [July 12, 2021, 11:05pm UTC](https://community.blackspectacles.com/t/addition-of-decibels/3280 "2021-07-12T23:05:10Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![liz.concepcion.arch](https://blackspectacles.com/uploads/images/13.png) [@liz.concepcion.arch](https://community.blackspectacles.com/u/liz.concepcion.arch)\ **Post date:** [July 12, 2021, 11:05pm UTC](https://community.blackspectacles.com/t/addition-of-decibels/3280/1 "2021-07-12T23:05:10Z")
I have been reviewing the fundamentals of sound and can’t seem to understand how to solve questions that use formulas with the “10 log” mathematical value. For example formula IL total=IL source + 10log _n_ If the values are: IL total=73dB + 10 log 8 How do I solve the equation? What is the total sound level? ---
**Author:** ![coachdarionziegler](https://yyz1.discourse-cdn.com/flex029/user_avatar/community.blackspectacles.com/coachdarionziegler/32/1272_2.png) [@coachdarionziegler](https://community.blackspectacles.com/u/coachdarionziegler)\ **Post date:** [July 16, 2021, 7:30pm UTC](https://community.blackspectacles.com/t/addition-of-decibels/3280/2 "2021-07-16T19:30:28Z")
Hi @liz.concepcion.arch , It seems some other candidates ran across this in the Ballast book. Check out their conversation on it at the link below: [https://are5community.ncarb.org/hc/en-us/community/posts/360038671773-Using-the-Calculator-on-the-exam-](https://are5community.ncarb.org/hc/en-us/community/posts/360038671773-Using-the-Calculator-on-the-exam-) In addition, the good news is that this equation isn’t on the formula’s list provided in the ARE 5.0 handbook so you won’t need to use it on the exam. See page 146 in the handbook for required acoustical formulas. ![image](https://canada1.discourse-cdn.com/flex029/uploads/blackspectacles/original/2X/8/8a177432221ac87c04e7f96e7949811a4aee9c0f.png) Hope this helps! -Darion