2(9+3)= 2*(9+3)= 18+6, but the equation in question is /2*(9+3)= 4.5+1.5. There are 3 factors in the original equaiton: 48*(1/2)*(9+3), each of which commutes with any of the others. The / sign just indicates: multiply by the multiplicative inverse.
" How would you solve 48/2(a+b)?"
48*(1/2)*(a+b)= 48*0.5*(a+b)=0.5*48*(a+b) = (a+b)*48*0.5 = 0.5*(48a+48b) = 24(a+b)...
"do you see 48/(2a+2b)? It's kind of whacky using the "/" sign instead of writing it out the way math should be written. "
As above... The / sign just means multiply by the multiplicative inverse. Then it's 48(0.5a+0.5b).
Yeah, but it looks stupid when we don't have a neat horizontal line between the numerator and the denominator as the good lord intended. :-)