Question 1013310
b = no. of boys
g = no. of girls
:
There are 72 members of the show choir.
b + g = 72
:
 There are 6 more boys than girls in the choir.
b = g+6 
:
How many girls and boys are in the choir? 
replace b with (g+6) in the 1st equation
(g+6) + g = 72
subtract 6 from both sides
2g = 72 - 6
g = 66/2
g = 33 girls
:
:
To confirm our answer, find the no. of boys
b = 33 + 6
b = 39 boys
then
39 + 33 = 72