Elijah builds model airplanes at a constant rate. He can build 5 model airplanes in 150 minutes, and 10 model airplanes in 300 minutes. How long would it take him to build 15 model airplanes.

450 minutes

Step-by-step explanation:

Since Elijah can build 5 model airplanes in 150 minutes. He can build 1 model airplane in 30 minutes. To find this you divide 150 by 5. The question asks for how many minutes it would take Elijah to build 15 model airplanes. Since 1 x 15 = 15 model airplanes, you use proportions and also multiple the time by 15, so 30 x 15 = 450 minutes.

t = 3

step-by-step explanation:

put t = 3 in this expression :

(3²-1)(3²-2)(3² - 3)(3² - 4) = 8×7×6×5 = 56×30 = 1680

the inequality is:

250c+180g≥950

step-by-step explanation:

let c denotes the number of days in a week   miyoko worked as a cryptographer.

and g denotes the number of days in a week she works as a geologist.

now we are given that she earns $250 for every day she works as a cryptographer,and earns $180 for every day she works as a geologist.

now miyoko's goal is to earn more than $950 this week.

hence, the inequality could be represented as:

250c+180g≥950