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P5 Mathematics

Question post on Thu, 17/09/2020 3:57pm

BigDevil · Answer 1 · Post on Sun, 20/09/2020 11:13am

Maybe my English was bad.

I took away 10 50-cent coins and replaced with 10 20-cent coins, and just couldn’t get the answer, until…

I took away 10 50-cent coins of value $5, and replaced with equal value of 20-cent coins, ($5 ÷ $0.20) = 25 coins

28u – 70 = 15u + 125

13u = 195

1u = 15

Value of 20-cent coins at first -> 3u × $0.20 = $9

Value of 50-cent coins at first -> 4u × $0.50 = $30

Sum of money in the box -> $9 + $30 = $39

hellowk · Answer 2 · Post on Sun, 20/09/2020 11:18am

hellowk Post on Sun, 20/09/2020 11:18am

Thank you. It’s like solving simultaneous equations.

BigDevil · Answer 3 · Post on Sun, 20/09/2020 6:20pm

You are absolutely right.

With 2 unknowns and 2 equations, it is indeed solving simultaneous equations.

hellowk · Answer 4 · Post on Sun, 20/09/2020 7:27pm

hellowk Post on Sun, 20/09/2020 7:27pm

Thanks alot for the answer. Appreciate it!

BigDevil · Answer 5 · Post on Sun, 20/09/2020 9:50pm

BigDevil Post on Sun, 20/09/2020 9:50pm

You are most welcome!