The shoe store has twice as many black shoes as it does brown shoes. The total number of shoes is 66. How many brown shoes are there?

x=number of brown shoes

2x=number of black shoes (twice as many black shoes as brown shoes)

so x+2x=66

add like terms 3x=66

solve for x by dividing 3; x=22

so there are 22 brown shoes and 44 black shoes (2 x 22 = 44)