The Maths Guide

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When we use negative values, we often use them to mean the opposite direction to what we were talking about.

Sara is 5 miles North of her house, and is travelling South at 2 miles every hour

How far North of her house is she in 28 hours time?

So in this question we are asked how far North of her house she will be.

So we can think of North as the positive direction and South then will be the negative direction

so 5 miles North is +5, and she is travelling South so we have -2 miles per hour for 28 hours

Answer +5 +28 * (-2)

= +5 - 56 

= -51

answer negative 51 Miles North.

in normal English we would say 51 miles South, but because the question is expecting the answer in terms of the direction North, our answer is negative 51

Sara is 5 miles South of her house, and is travelling North at 2 miles every hour

How far North of her house is she in 28 hours time?

So in this question we are asked how far North of her house she will be.

So we can think of North as the positive direction and South then will be the negative direction

So 5 miles south is -5 (negative 5), travelling north is +2 (positive 2) miles by 28 hours

= -5 + 56

= +51 miles north

Answer +51

Similarly

If we want our answer to be above ground, we can use negative values to show a distance below ground.

If we want our answer to be how many people got on a bus, we can use negative values to mean how many people got off the bus.