Nina changes \(450\) euros into dollars when \(1\) euro \(=\$1.08\). She then spends \(\$312.50\). Work out how many dollars she has left.
Question 1 Report
Nina changes \(450\) euros into dollars when \(1\) euro \(=\$1.08\).
She then spends \(\$312.50\).
Work out how many dollars she has left.
Answer Details
Work through the two stages in order: convert the currency first, then subtract the spending.
The rate says that \(1\) euro is worth \(\$1.08\), so each euro becomes \(1.08\) dollars and \(450\) euros become \(450\) lots of \(\$1.08\):
\[ 450\times 1.08=486 \] [M1]
Nina therefore starts with \(\$486\). Subtracting what she spends:
\[ 486-312.50=173.50 \]
She has \(\$173.50\) left. [A1]
Decide between multiplying and dividing by checking which currency is worth more. One euro buys more than one dollar, so the number of dollars must be larger than the number of euros. An answer of \(450\div 1.08=416.67\) fails that test and would convert dollars into euros instead.
Keep the working in dollars once the conversion is done. Subtracting \(\$312.50\) from the \(450\) euros mixes two different currencies and is not a valid calculation.
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