Question

Please help. I’ve been stuck on this question for a while. I would really appreciate it if someone could help me please. :)

(Simultaneous equations) James has $10 in 5-cent and 10-cent coins in his change jar and counts 157 coins in total. How many 10 cent coins does he have?

Answer 1

43 10 cent coins

Explanation:

let x represent the number of 5 cent coins and y the 10 cent coins.

Since we are dealing in cents change $10 to cents, that is

$10 = 10 × 100 = 1000 cents

Now we can write 2 equations to represent the situation.

x + y = 157 → (1)

5x + 10y = 1000 → (2)

Multiplying (1) by - 5 and adding to (2) eliminates x

- 5x - 5y = - 785 → (3)

Add (2) and (3) term by term

(5x - 5x) + (10y - 5y) = (1000 - 785), that is

5y = 215 ( divide both sides by 5 )

y = 43

That is there are 43 10 cent coins