Use substitution to solve the system of equations.
2x+y=4
-2x+y=-4

45% of the trees in a park are apple trees. there are 27 apple trees in the park. how many trees are in the park in all?

The amount spent on food and drink by 20 customers is shown below what is the modal amount spent and the median? 40 25 8 36 18 15 24 27 43 9 12 19 22 34 31 20 26 19 17 28

Afactory buys 10% of its components from suppliers b and the rest from supplier c. it is known that 6% of the components it buys are faulty. of the components brought from suppliers a,9% are faulty and of the components bought from suppliers b, 3% are faulty. find the percentage of components bought from supplier c that are faulty.