A trader has a mixture of 5c and 10c coins. He has 50 coins in all, with a total value of $4.20. How many of each coin does he have?

16 5c coins

34 10c coins

Step-by-step explanation:

(I prefer to use whole numbers)

5x + 10y = 420

x+y=50

multiply the bottom problem by -5

5x +10y =420

-5x -5y = -250

combine the problems

5y = 170

divide by 5

y = 34

that means x = 16

34 10c coins

16 5c coins

-- Gage Millar, Algebra 1/2 tutor

step-by-step explanation:

if you want to solve percent error follow these steps.

1. subtract the accepted value from the experimental value.

2. take the absolute value of step 1.

3. divide that answer by the accepted value.

4. multiply that answer by 100 and add the % symbol to express the answer as a percentage.

if you want to solve percent of change just do this.

1. work out the difference (increase) between the two numbers you are comparing.

2. divide the increase by the original number and multiply the answer by 100. if your answer is a negative number then this is a percentage decrease.

hope this : )