Question

Samuel has 10 coins that add up to $3.80. Some are 50 cent and the rest are 20 cent coins. How many 50 cent coins does he have?

Answer 1

6 coins of 50cent

Explanation:

Information we have:

1. x number of 50cent and y number of 20cent added up to 380cent.

2. x and y is 10coins

eq1 : 50x + 20y = 380

eq2: x + y = 10

write eq2 to y in term of x

y = 10 - x -> eq3

replace eq3 into eq1

50x + 20(10 - x) = 380

50x + 200 - 20x = 380

50x -20x = 380 -200

30x = 180

x = 180/30 = 6