If we stack two truncated tetrathingies together so they anti-fit, how many ways are there to color in the bottom ttt using the same four colors as the top ttt... so that no two chunks of the same color are touching

Justin plans to spend $20 on sports cards. Regular cards cost $3.50 per pack and foil cards cost $4.50 per pack

number of packs of regular cards =r and the number of packs of foll cards = f

Cost of Regular card = 3.50

Cost of 'r' packs of regular card = 3.50r

Cost of Foil card = 4.50

Cost of 'f' packs of Foil card = 4.50f

Justin plans to spend $20 on sports cards so the sum of cost of regular and Foil cards should be less than or equal to 20

The inequality becomes

3.50r + 4.50f <= 20