Welcome to the ODK forum, @Tarang_Khurana! We're glad you're here. When you get a chance, please introduce yourself on this forum thread. I'd also encourage you to add a picture as your avatar because it helps build community!
for opt_q5_total instead of...
${opt_q5_a} and ${opt_q5_b}
try...
if((${opt_q5_a}='1' and ${opt_q5_b}='1'),'1','0')