A school choir needs robes for each of its 30 singers. Currently, the school has only 12 robes so they decided to buy the rest. If each robe costs $2, how much will the school spend?
Let's think: The school needs to buy 30 - 12 = 18 robes. So the school will spend 18 x $2 = $36.. The answer is: 36.

John reels in 3 crab baskets a week. Each basket holds 4 crabs. He collects crabs twice a week. Each crab sells for $3. How much money does he make?
Let's think: He collects 3 * 4 = 12 crabs each time. He thus collects 12 * 2 = 24 crabs a week. So he makes 24 * 3 = $72 a week.. The answer is: 72.

Denver uses 7 pieces of wood for each birdhouse and he pays $1.50 for each piece of wood. If he makes a $5.50 profit per birdhouse, how much will Denver charge to Danny for buying two birdhouses?
Let's think: The cost for making one birdhouse is $1.50 x 7 = $10.50. So the selling price of one birdhouse is $10.50 + $5.50 = $16. Thus, Denver will charge Danny $16 x 2 = $32 for the two birdhouses.. The answer is: 32.

Mario's salary increased by 40% to $4000 this year. Bob's salary from last year was equal to three times Mario's salary this year. If Bob's current salary is 20% more than his salary last year, what is his current salary?
Let's think:
Last year, Bob's salary was equal to three times Mario's salary this year, meaning Bob was earning 3 * $4000 = $12000. If Bob's salary increased by 20% this year, he is earning 20 / 100 * $12000 = $2400 more. Bob's total salary this year is $12000 + $2400 = $14400.. The answer is: 14400.