X+ y = 4 x - 2y = -5 if the first equation is multiplied by 2 and then the equations are added, the result is

Martha is training for a duathlon, which includes biking and running. she knows that yesterday she covered a total distance of over 55.5 miles in more than than 4.5 hours of training. martha runs at a speed of 6 mph and bikes at a rate of 15.5 mph.

The students at jefferson middle school are raising money for a charity by selling t-shirts and hats. the number of t-shirts sold was 3 times the number of hats. the profit was $5 for each t-shirt sold and $2.50 for each hat sold. the students raised $840 for the charity. they used the system below to analyze their success and found the solution to be (144, 48). 5x+2.50y=840 x=3y how much did they earn from t-shirt sales?

The function p(x) = –2(x – 9)2 + 100 is used to determine the profit on t-shirts sold for x dollars. what would the profit from sales be if the price of the t-shirts were $15 apiece?