Jenny has a strawberry lace sweet. She gives 425 mm of it to her sister and 387 mm of it to her brother. She still has one third left.

Question

How many millimetres of strawberry lace left?

Answer 1

Let's denote the total length of the strawberry lace sweet as \( x \) mm.

Jenny gives 425 mm to her sister and 387 mm to her brother, so the total length given away is:
\[ 425 \, \text{mm} + 387 \, \text{mm} = 812 \, \text{mm} \]

According to the problem, she still has one third of the strawberry lace sweet left. This means the remaining length is \(\frac{1}{3}x\).

The total length given away plus the length she has left must equal the total length of the sweet. Therefore, we can write the equation:
\[ 812 \, \text{mm} + \frac{1}{3}x = x \]

To solve for \( x \), first isolate \( x \) on one side of the equation. Subtract \(\frac{1}{3}x\) from both sides:
\[ 812 \, \text{mm} = x - \frac{1}{3}x \]

This simplifies to:
\[ 812 \, \text{mm} = \frac{2}{3}x \]

Next, solve for \( x \) by multiplying both sides by \(\frac{3}{2}\):
\[ x = 812 \, \text{mm} \times \frac{3}{2} \]
\[ x = 1218 \, \text{mm} \]

So, the total length of the strawberry lace is 1218 mm.

Now, we need to find how much she has left, which is one third of the total length:
\[ \frac{1}{3} \times 1218 \, \text{mm} = 406 \, \text{mm} \]

Therefore, Jenny has 406 mm of strawberry lace left.